I have never installed any. What is the usual bonding medium? Or are there choices as I suspect. I have seldom seen many available used. Or surplus new. Perhaps a different story if I really went looking.

As I read your post I have been considering how to build some unusual form of a larger shower for some time. This in a basement washroom that is not started yet. Other than the fixture drains are in the concrete floor.

I immediately though I could use these if I can find them at the right price. Although it would take considerable thought to decide.

I would have no issues drilling the blocks for all the nozzles and fixtures etc. Visually you would see the feeds in a distorted fashion. If you had strong diffused lighting outside the walls the shower might glow. There are many possible effects that occur to me if used..