When mine eventually needs access creating I plan on installing magnets for a hidden access panel.
You can get magnets for the backs of your tiles and just have to use caulking instead of grout around the tiles you can’t to be removable.
Fortunatley we had some left over tiles and I have kept them purely for this very reason.
Might not be helpful unless you can get the old tiles off in one piece and make an access panel yourself, or find some extra tiles to replace ones you have to take off.
You can get magnets for the backs of your tiles and just have to use caulking instead of grout around the tiles you can’t to be removable.
Fortunatley we had some left over tiles and I have kept them purely for this very reason.
Might not be helpful unless you can get the old tiles off in one piece and make an access panel yourself, or find some extra tiles to replace ones you have to take off.