Right so just installed xscreensaver - automatic blanking and locking is indeed broken BUT it does display all the pretty animations just fine! (at least on Sway)
Don’t really have time to mess around with it but maybe try figuring out which mechanism is used for screen locking in your environment (in Sway’s case it’s swayidle) and get it to start xscreensaver right before calling the real locker program?
BTW you can get xscreensaver-settings to come up by unsetting the WAYLAND_DISPLAY variable:
Philosophical BS: I don’t think it’s correct to say that Wayland doesn’t support screen savers, but rather that it doesn’t support XScreenSaver, or, more accurately, the mechanisms it uses for screen locking and idle-detection.
As others have pointed out, equivalent functionality has already been implemented and is used by various screen lockers. What appears to be missing is something to take this functionality, and display an animation instead of just locking the screen.
I noticed that all of XScreenSaver’s animations are actually separate binaries in /usr/lib/screensaver/ so we basically need a locker that speaks Wayland’s locking protocol, but also takes and runs those binaries in full screen mode.
Or maybe XScreenSaver’s dev can be convinced to add support once the protocols are stable?