How do you upload a snapshot?
Basically, as you said. Mount the data somewhere and back up its contents.
I back up snapshots rather than current data, because I don’t want to stop the running containers that read and write from that data. I’d rather avoid the situation where the container is writing data while it’s being backed up. The back up happens shortly after the daily snapshot is made so the difference between current and snapshot data is small.
I do the same. Fedora on my laptop because I want a balance of stability and having the newest features. Servers run Debian, because I don’t have time to fix and update things.