Absolute beast, but it's no longer manufactured and you probably gonna take used one.

I've recently restarted playing EU4 on my old(10y+) Fedora PC. The last upgrade it took was Radeon RX 580 ~ 5y ago: https://en.wikipedia.org/wiki/Radeon_500_series.
OTOH AMD recently announce they stop supporting Vulan on the prev generation of cards, Polaris and Vega: https://www.phoronix.com/news/AMDVLK-2023.Q4.1-Released

Likely all the same for EU4 which never cared for AMDVLK?

-> You can go with pre-RX 5000 cards, RX 500 cards will work just fine.
Likely a better idea to take a card of recent generations if you want to stay green (energy efficiency), unless you play in a cold cabin most of the year.

amdvlk is niche. Mesa gonna support and is considered as better solution.

not sure where you're located, but this would be overkill for EU4 at $120.00 USD https://www.newegg.com/xfx-radeon-rx-580-rx-580p8dfd6/p/N82E16814150803

Edit: regardless of which AMD gpu you get, before swapping cards make sure to set the nvidia driver back to the default nouveau driver so the proprietary nvidia driver is uninstalled. it will save you some headaches.

Secret sabotage? nvidia/ms/intel different res/outputs now we can game better w/ AMD
If say nvidia or whoever kept swapping out your display drivers and audio etc.. with lower quality settings and 'streaming' to use low bit depth and no bandwidth so it looks like butts like fake hardware companies on your real bought from the AMD website or a listed reseller AMD hardware.. well rather than guess at what settings specifically.. we can 16bit agfaswop color management in windows maybe also default the rendering intent and maybe try using absolute colormetric? 12bit ScRGB virtual device profile is an option too. But using INFINITY PIXELS and INFINITYRESOLUTION and INFINITYBIT DEPTH... seems to help a fair bit. you will wanna enable infinitycache and fabric and vcache and 3dnow and all that cool AMD stuff and whatever else first though.. theres a heap of stuff you maybe need to do to get it working well but i can game fantastic on an LG V60 mobile phone with dolbyvision just by dropping some config.ini files in there.. works similar on PC but for windows to really work you need to change directx/vulkan/d3d featurelevels and waveout physically persistent render multimedia audio and video visually vulkanrenderdolbyvisionAC9AC3DRCprinteddirectlytodisply or whatever you think looks good in rendermodetrue and all that with amdprorender/amdfidelityfxsuperresolution and things like amd cinema4d or i use cinema9d.. well you get the point.. when it uses all the possible resolutions at once.. it gets super detailed when professionally rendering your games in realtime.. but for some reason my games look like these low quality mikumiku dance renders and netflix stuff.. and not like uhh highest quality unity renders?
https://gofile.io/d/OYrgw5
mediafire com/file/fpflaf2l0v89jrd/infinitybitdepthinfinitygraphicsinfinitypixelsinfinityresolution.rar/file
https://pixeldrain.com/u/JJFZ4T1z
try my config html / xml / ini files just copy two dozen into documents folder if youve android/linux/windows. BUT you require AMD CPU/GPU so if its any true dolbyvision device so samsung phones.. LG and some lenovo.. the list is actually fairly short for tablets/computers etc with real dolbyvision which means real AMD. but you can buy AMD hardware via amd website and their authorized resellers on the site should be fine.
i lazy and put all 3 extensions and put all 36 in documents and maybe again in videos folder up to you really give it a go and try. the xml 16bit dos old way of typing in the word HTML seems to work best because fake intel fake nvidia and all this better than rtx 1:1 universe space program quality stuff map the universe in medical quality details was uhh 1970s stuff from AMD? So its supposed to look WORLDS better or 3x better at minimum in my RDNA 3 than any dolbyvision TV or camera.. but i dont get to see that because fake intel fake nvidia.. you see a keyboad has 8bit 0-255 ascii characters.. but COMPUTERS old DOS ones use those ascii symbols in these groups called 'words' when assembled.. so this assembly of symbols is known as assembly language.. to use the 0-255 keyboard symbols you hold the ALT key and +0 and 4 digits numbers for the ascii l33t speak of 90's internet chat rooms and ascii art.. but why is it 4 digits long you ask? well CPU extensions and maths and complicated scientific calculators can do hundreds of football fields maths at a button press precicely and an AMD computer is way better than that and has a ZEN CORE.. all the maths functions etc in the universe.. SO its nonunicode ascii support in the date and time languages of windows MUST NOT MAKE YOUR VIDEO BETTER WHEN TICKING 'eperimental beta 8bit unicode' that just means fake intel fake nvidia fake microsoft third world wangs are all up in your computer choking its performance to be like the 0 bit depth 0 hardware not maths not computers that are the dumbest things ever.. these complex maths cores from AMD are a bit more expensive than scientific calculators.. get paired up with good old fashioned transistor radio technology of actual super scifi more complex advanced transistors.. for lightwaves/soundwaves.. so when it says TRUE AUDIO on the box.. like it does ALL electromagnetic fields and optical internet/wifi/satellite.. any sort of radiation or radio waves.. xrays gamma rays.. remember 90's gaming on AMD with gamma radiation TV settings for your games? yeah nvidia suck and blow at the same time! ha fake software rtx pretend light when AMD games are supposed to be true digital DSLR but better reality emulation video games are supposed to be ACTUAL VIDEO OMG! but when i game.. its awful unicode isnt even 8bit.. and its maybe not even 0-255 ascii because criminal ♥♥♥♥♥♥ hacker f4gs!! 0h n0es! so .. i dunno how to fix it.
with ♥♥♥♥♥♥ fake 3d software unreal bleargh. or unity which is better.. but has similarities to unreal.. or others i dunno houdini or whatever blender.. blender is maybe a partly once was real 3d with a fake nvidia 2d photoshop overlay output so they call it blender. the reshades and stuff isnt even directx9.
so maybe some akashi youtube channel MMD dance video renders or cabbagebai youtube channel and its mmd renders of genshin/star rail whatever. Or highest quality unity renders or stuff like sakura rabbits youtube channel heres what i did in unity this year or whatever is how its SUPPOSED to look using the fake intel fake nvidia software but yeah thats about as good as fake nvidia fake intel fake microsoft software can go because of nvidia and intels lack of hardware.

which are totally random terrible examples i picked but have light sparkles shiny and metallics.. i .. end up having my games look like lame stuff thats not quite like that.. and those things are universes away from having better than the best dolbyvision TV's and cameras.
so uhh i dunno how to fix it but im hoping you guys can get some clues from my hints and my config files i linked. try making a custom resolution in the AMD adrenaline control panel and changing the timing formula also see what looks best? maybe GMTF or CVTreduced blanking? not sure. if youre in sydney i've a 5700xt i could sell you 8GB powercolor red devil factory OC. otherwise i'd recommend price /performance maybe a RDNA 2 6700xt but i think the compute units count is how high the digital/analog conversion is.. also the number of rear HDMI ports maybe improves the audio quality when outputting over HDMI.. especially if you use multiple GPUs perhaps? not sure.. but even an APU from AMD can maybe rip intel and nvidia to pieces and ray trace before rtx was a thing.. in old like sonic racing games or world rally WRC 7 or WRC 10.. or maybe WAYYYY OLDER STUFF.. in particular of interest to me is things that are non rtx titles so wont look as 'cool' or as ray traced like honkai impact 3rd or genshin impact free mobile titles.. but for 'realism' and cool graphics you want older 2013 titles like world of tanks and world of warships.. just go the warships free to play one.. WOT kinda sux.

Thanks all for your inputs. I now have a Radeon RX550 up and running, Steam installed, EU4 in on, all is well. Now, I just need to re-learn the game : I've been off it for two years…

enjoy!