I would wallpaper it.

Walls are textured so they would need to be skim coated before applying wallpaper.

I want to add molding to my bathroom

Why? What outcome do you want?

" Box frame/ vertical shiplap/ board and battan/ beadboard, etc. "

None of those are "moulding". What look are you trying to accomplish? Were it me, the first thing I would do is get rid if the texture on the walls and ceiling (if there is texture on the ceiling and I would assume there is since it is on the walls). I really that may be all you need.

Its a south west thing to have textured walls. Ceiling is smooth actually. I just want to give it an oomph. Did beadboard downstairs.