Not my main rig, but my most unusual is 32-bit Yocto Linux on an Intel Edison that I got for free from a college professor that worked for Intel.
Yocto is awful. I mean it has a niche I guess, but there is basically no package manager. Somehow I managed to install a Rust toolchain on it, but it couldn't build the web server I wanted to run on it.
I'd much rather have a Pi running a sane distro.
NixOS is at least starting to work on a new wiki. The old one is gone and is only accessible from archive.org.