I make the specification of non-linux because otherwise this would just become a thread full of obscure distros that do the same thing as a million other distros.
Some lesser known OSs:
- AROS - based on Amiga OS, has some derivatives like IcarOS and MorphOS
- Haiku - based on BeOS
- Redox - Unix-like, made in Rust (might technically count as linux?)
- Serenity - Unix-like, very late 90s look and feel
- Kolibri - Tiny OS, the image is ~44MB. It also has a smaller version that fits in a single floppy.
- PhantomOS - When 3 Russians decide to turn everything about a typical OS upside down.
At a quick glance on the wiki page, it sounds like something that would work great if we needed hundreds “dumb” terminals that just connected to a central server and received/displayed the output back to the user
Incorrect. That’s X11; we have that. Plan 9 is a little hard to explain quick, but I gave some examples already of stuff that is trivial with it that’s a big weird difficulty on other modern systems, but in addition to that the whole UI and the terminal / editor also work radically differently to how Unixlike systems do it.