@skoranda If you'll allow me to pitch in, I've been using Garage for almost 3 years now and it's been pretty nice.
Managing it can be a hassle at first, since it's CLI only (and some of the commands can be a bit "annoying" to understand) but once you get the hang of it, it's pretty simple.
Updates are very simple (just create a backup, replace the single self-contained binary, and off you go), it has been very stable and fairly performant (for as performant as my server's storage is).
I haven't used any clustering yet but it doesn't sound difficult to set up either.
The community on Matrix is also very friendly if you need any help.
All in all, can recommend.