How to obtain all the achievements with only one save / reload.
All Mission Achievements Guide
While the other guides are helpful, they are rather chaotic, so I made a chart that shows how to obtain all the achievements with only one save / reload. My guide shows how to unlock “The Nuclear Option” while aligned with the Brotherhood, but I also indicate when to diverge from these steps, if you want to play the Railroad or Minutemen endings.
Chart that Shows How to Obtain All the Mission Achievements with Only One Save / Reload
What about DLCs Mission Achievements?
Achievements from the Far Harbor DLC are not missable so if you just continue with your playthrough you will get them all.
Achievements (“Raiding for a Living” & “Hostile”) from the Nuka-World DLC however are missable if you become enemy with raiders (murdering any gang member after you’ve exited the Gauntlet). So in short do not do not become enemy with the raiders before completing Story achievements and “Raiding for a Living” & “Hostile Takeover” and you will get them all!