They're frequently built in tho so you're up for demolition, plumbing, carpentry or masonry, tiling, and painting, as well as the purchase of the new tub.
Japanese hotels have a small bathroom blow molded in a single casting. The whole room is one piece of plastic, no joints, with a sink and a toilet installed later. It's wild. Super effective against leaks, I guess, but if you ever had to replace it you'd have to tear a side off the building to crane a new one in.
Johnny, I say you take some old house paint, throw some sand in it, and tell 'em it's the latest thing in non-slip safety coatings.