A waterflow sensor makes the most sense to me too, but it doesn’t have to be inside the pipes. A microphone glued to a pipe should be able to detect the vibrations due to waterflow and hardly anything else.

Perhaps combine with a motion sensor to see if the lights should be on at all. Then the microphone only switches between modes.

2009 maybe doesn’t sound super long ago, but it’s 17 years, that’s almost the midpoint between now and when operating systems became mainstream.

The kind that is beginner friendly, where I can host some stuff like Jellyfin, some storage, git or similar, etc. Just for me and friends/family to access.

What is nodeBB? A lemmy or piefed alternative or a whole different thing altogether?

There’s plenty of perfectly fine distributions out there. Mint is an easy choice, easy to get started with, big community that probably already has answered the questions you might have and otherwise you can ask them. Many more gaming focused people use Bazzite, not sure what it offers on top of a basic, well working environment.

The Nvidea graphics card could cause issues since drivers tend to not be supported well. Again, you’re most likely to find help for the bigger distros such as Mint and Bazzite.

Regardless of which distro you choose, just try it and see how it goes. Dual boot can be a nice starting point (but make sure you get the partitioning right before installing anything!).

Do I understand it right that when it comes down to it, this is a different implementation of the same thing (rendering)? I assume that this is mostly relevant for software engineers and that the end user only notices some differences in speed, if at all?

Very true about the Wayland vs X11 knowledge. I didn’t learn about that until quite a while after startint to use Mint. Even know I don’t really umderstand what it does (something rendering and windows?), it doesn’t seem to make much of a difference in day to day use anyways.