BTRFS for the OS partitions, ext4 for /home, tmpfs for /tmp. I rarely need to use snapshots, but I do use a rolling release. It’s one of those things you don’t need until you really fucking NEED it. Tumbleweed support is great - I can roll back a bad update in about as long as it takes to reboot.
IIRC, Qt comes with its own declarative language. That might be why you can’t find any bespoke ones.