wow.

they make all colors of plate covers (you'll need to switch out the outlet too)

you could do a black or dark brown. they have those at the big stores.

fluffy white rugs. maybe a large piece of black/white art over the toilet? like, tall! to hide as much of that tile is possible.

is the ceiling tiled as well?? is this a steam shower?

if so, that light will have to be wet-rated.

Honestly I wouldn't bring in anything else to enhance this room. I'd save every dime in order to rip it out.

at some point, will this be demoed?

Since you are not able to redo it at this time, then yes, keep the white towels and add a white rug to lighten up the space. It might be tricky to hang art on those tiled walls. Perhaps you could replace the thick framed vanity mirror with something more simple or frameless. Also, new lighting may spruce up the space.

as for hanging the art, they do have sticky art hangers that can be used. (Command strips?) using an acrylic type of frame that's light would be fine.

IF the frame is heavy, and if they plan on demoing, drilling into the tile to hang a picture isn't a big deal. I can't imaging one tiny hole in that tile is going to make it look any worse.