The new ISO is coming very soon. We've just been busy with consulting we do to support the project and there were some issues with gpg2.
Wayland is one huge reason why we aren't even calling this "beta". Wayland is absolutely part of the plan. We are working on integration now.
Flatpaks: probably not. Different vision. Flatpak is an 'appstore' type model, not sure we will want that in Subgraph OS, but it's worth a deeper investigation than the thought I've given it so far. There are things in Flatpak that we can benefit from, such as the UI advantages of "Portals". We'll probably be adding support for it to Oz.
Good to hear you're considering it. It may be worth looking into appimages as well. They don't seem to focus as much on security, but perhaps their isolation is better? Flatpaks seem to share quite a bit with each other, and I worry it may create another X11-situation. Flatpaks may still be better overall, though, if they can also have good isolation.
I doubt you should even bother with snaps. They don't seem to be that well supported outside of Ubuntu, and I doubt they will ever be.
We use Xpra to do desktop isolation for now, by the way. It's similar to Qubes' display mechanism, but we didn't write it, and don't really like it as a security control. Just serves as PoC until we can jump to Walyand.
Therefore Subgraph OS isn't in the worst possible x11 situation, which is the default for every desktop Linux except I think the most recently released Fedora.
Re: iso / updates, we have rolling updates. Installed users are kept current if they install the OS and regularly apply updates and do dist-upgrades.
Wayland is one huge reason why we aren't even calling this "beta". Wayland is absolutely part of the plan. We are working on integration now.
Flatpaks: probably not. Different vision. Flatpak is an 'appstore' type model, not sure we will want that in Subgraph OS, but it's worth a deeper investigation than the thought I've given it so far. There are things in Flatpak that we can benefit from, such as the UI advantages of "Portals". We'll probably be adding support for it to Oz.