What about the vinyl tile decals. To make the stall look tiled.
Maybe just add a new shower curtain
that's what we have and I don't try to camouflage the shower itself, but make the rest of the bathroom look good. Our shower even has the pipes on the outside! I did make a sink skirt and a shower curtain.
Recaulk every seam, sand every edge and repaint as needed. Use a nicer shower shelf, soap dish, safety bar, and non-slip rug inside the shower. Buy a new shower curtain, rings, rugs, curtains, and coordinating decorations. Replace or clean old soap, lotion and liquid soap bottles, razors and other visible toiletries. Get and use a squeegee ($1 at Dollar Tree) on shower doors , windows, and walls— will drastically cut down on cleaning time if you use a squeegee every single time. Oops! Don’t forget a shower curtain liner. Enjoy your “new” shower and bathroom!
A pretty shower curtain makes a big difference.