For example, the helmet you can steal from the Prydrwen. I'm curious if you can find all pieces of the X0-1.
No, all power armor spawns are based on level, except for the BoS and Atom Cats. However, they have T-60, not X-01.
You can go to 35 Court and can find a full set there through 35 Court is unmarked you can find it west of the customs house