The ONLY one that works is Raspberry pi os Legacy available from the rpi flasher. What other OS would work?
Not sure it counts as a separate OS, but I run DietPi on all of my pi’s. It’s a super stripped down version of Debian/RPiOS. Everything you need, nothing you don’t.
DietPi is great, I also run it on all my devices. Highly recommended!
That’s certainly tricky since the Zero’s CPU supports ARMv6 with VFP2 as that likely eliminates Debian based operating systems unless there is a version with packages built for VFP2 instead of VFP3, like Debian has. Doesn’t look like Ubuntu has had a version that supports the Zero W’s CPU since like 12.04 which is going to be incredibly out of date and unsupported even if it does work.
FreeBSD is supported but no wifi: https://wiki.freebsd.org/arm/Raspberry Pi