How does it compare to hyprland in it’s current state regarding stability, features and support?

Distrobox is probably what you’re looking for.

Full desktop environment with decent window tiling.

Isn’t this what Flatpaks are doing?

it doesn’t even host it’s own repos

Yes, and that’s a good thing, otherwise it would be like Manjaro.

EndeavourOS is perfect if you already know your way around a Linux system but don’t want to spend the time and effort to setup Arch.