What wall finish behind wall hung toilet and vanity? – GreenBuildingAdvisor

hi, I’m looking for advice on what wall-board & finish to use behind a wall hung toilet and adjacent vanity. I’m concerned gypsum might compress/crush over time behind the toilet. I read that some wall-hung toilet manufacturers recommend plywood for this reason, but then I’m concerned about how to handle the seam between the plywood and surrounding drywall. Ideally, I’d also like to find a wall finish that could double as the backsplash behind the vanity. I prefer that more streamline look, especially b/c the vanity will abut the side wall, so a backsplash would need to be an L-shape.

Option 1 is to tile it. It’s just hard to know where to stop, especially with the vanity abutting the side wall. And I’d be locked into the tile color.

Option 2 is to use a material like MDO or hardiebacker, mud and tape seams, skim coat if needed, and paint it. Interestingly the Hardie website says hardiebacker is suitable as a painted surface. But would I be able to transition from that to drywall without cracking? And do you think it’d be suitable for a backsplash around a bathroom vanity? Also which material would you use & how exactly would you treat the joints & prepare the surface?

Thank you!

Ben