I got "Made in New Haven" without doing any non-required Dahl Headlands quests. And for anyone that reads this, in case it is helpful: there is a stretch of play after completing all the missions in the rust commons before you get to the Vault Boss. When I did my very first playthrough on GOTY, I made a backup copy of my main game save when I got to the Vault Boss, then I renamed the file (while the game was closed, according to the naming convention in the save folder) and the game recognized that as a separate save file playthrough. (Continued below)

(Continued from above) So when I eventually imported into Enhanced, I had my main 2.5 playthrough and I had my copy which was at the Vault Boss. I used the 2.5 import to do the bulk of the Enhanced achievement cleanup for the main game and DLC. Then I used a brand new character to do all the missions in the Arid Badlands and Rust Commons (and the main story missions only in the Dahl Headlands) then, after completing that part, I was able to load up my imported Vault Boss save and do that, skipping the achievment-less stretch in between.

Found this 3 years later - thanks. I got the 1,000,000 achievement after selling one gun with my imported 2.5 playthrough character. Not sure if it was a gun that sold for that much or not, but I didn't need to do it on a new character.

You might be right. I just wanted to add the information I could to help people in the future. I don't know what the counter would be. We used our imported characters that we did the character specific achievements on and used them for our new playthrough. We unlocked Made in Fyrestone even though they already had a couple of story missions done. Perhaps it's just one or more story missions that must be completed as well. Another note, Leaving Fyrestone is NOT required for the achievement to pop. It popped for us with that mission still active.

I assume there's some hidden counter that counts the number of missions you've completed in each area - but this number isn't transferred over from old to new.
The "Paid in..." achievements work because you can finish any five missions which increment the counter, but you can't finish enough for the "Made in..." achievements because you already did the story missions in old game.

Yes I am sure we did everything for Made in Fyrestone. The only thing I haven't done is Dahl Headlands. I looked up the achievements themselves, wrote down every mission required and marked them off as we got them. After completing all missions, we did not get an achievement.

The only thing I can figure is to try to finish Dahl Headlands as well. To note, the mission list I made and checked off as we went worked for the achievements the first time. We haven't actually done the Made in New Haven mission list and don't see much reason too as Fyrestone didn't pop.

We will be cleaning up random achievements on Enhanced today. Due to your guide we left the Vault boss alive in Playthrough 2 so we can kill it for the achievement on our mains. We can verify what does and doesn't work if you have any more questions. I am just as mystified as you as to why Paid in Fyrestone works but Made in Fyrestone doesn't.

Are you sure 100% you've done everything for "Made in Fyrestone"? I would've thought that would work, unless it's counting Story missions as well(?). I'm not actually sure what counds as "all missions".
It could also be that those achievements just don't work in Playthrough 2, though that seems unlikely if you were able to get "Paid in Fyrestone".

My buddy and I just finished the first game and imported our characters. We purposely did only the main series missions in Playthrough 2 and did not kill the final boss.

We were trying to see if you could pop the all missions achievements without doing a new playthrough on Enhanced. When we completed all missions for "Made in Fyrestone" the achievement did NOT pop.

It was nice to test but we have confirmed that a new playthrough is required on Enhanced. If you have more than 5 optional missions available in a playthrough though, you can pop those achievements.

If we're being technical, a single imported character can, with help from a friend or two for multi-player achievements, unlock 75 out of 80 achievements. You will only be missing the character specific achievements (for the classes you aren't playing), Made in Fyrestone, and Made in New Haven.

Alright thanks :)

Yeah, you just need a playthrough (1 or 2) with less than 5 missions completed in the Arid Badlands since I don't believe there's any way to re-trigger those achievements.