This is a feature in moonlight I've missed as I've tried moving over to Steam remote play.

I have an ultrawide screen as my main gaming screen, but often like to stream to my 4k TV, which turns into a mess with an ultrawide. So I have to change my main display to my 4k, then switch it back when I'm done. You can sort of fix this by using Steam Big Picture, but it just cuts 3 steps down to 1. Ideally we could have zero. This could easily be added in the Advanced Host option for Steam Remote Play settings.