It’s mentioned that Ubuntu may have issues. None of the developers working on this project use Ubuntu, therefore no one has bothered to make sure it works on Ubuntu.
The recommended distros list exist for a reason - Fedora/Ultramarine, Debian and Arch/Endeavour are all used by the devs on Chromebooks, and openSUSE and nixOS are popular with the community as well. It’s a safe bet to just choose what others use.
If you want to use Ubuntu, you can always use it on another machine;)
I might try a different distro then. Are any of the distros you listed better supported than the others? Looking for whatever is going to have a lightweight window manager available and require the least amount of tinkering
Fedora probably. Has the benefit of not being Arch, and doesn’t require a custom kernel like Debian.
Fedora has i3 and Sway spins, anything else you’d have to install yourself. I guess you could download the LXQt spin and just use Openbox without the LXQt part as well.
If you want a truly beautiful preconfigured window manager distro, check out Archcraft.