I don’t know too much about Vanilla OS, is it not possible to install your own DE or WM?

I’m less interested in Vanilla OS since it’s based on Ubuntu and I’d rather not support / rely upon anything Canonical if I can help it.

Silverblue (+ spins) seems like the best option since it is the most mature, most popular, and is a community run distro. Of course Redhat pours a lot of resources into the Fedora project since it’s upstream RHEL, and so does SUSE for MicroOS. But honestly if Redhat/SUSE were to disappear tomorrow, I think Fedora and OpenSUSE would be fine, whereas I can’t say the same for Canonical+Ubuntu (and thus their descendants).

edit: After looking more into Vanilla OS, it looks very nice! Funnily apx addresses excatly the issues with distrobox pointed out in this thread by @mogoh@lemmy.ml. They also plan on moving from being Ubuntu based to Debian Sid based, which would be even better than Fedora as Debian is a true, 100% community backed and time tested distro (though still of course much corporate support).