Transfer from Snap Docker to Deb Docker

I’m just getting started with Docker. I’m running it on Ubuntu Server 20.04. I didn’t realize that Ubuntu packaged Docker as a snap container or the various issues with Snap. Of course, I have a handful of containers that all have their data mounted in external docker volumes, since permission issues made storing their volumes in /home above my head.

So now I’m leaning towards migrating from snap. I would have expected this to be easy and to have guides everywhere, but shockingly enough there’s virtually nothing out there.

Can anyone lead me down the right path to backing up at least the external volumes, if not the containers with the volumes, in a way that is then restorable once I’ve purged the snap versions from the server and re-installed via apt?

Ideally, I’d like to backup the paths as well (e.g. “namedExtVolume:Container1/config”) so that it’s a one-line (or one line per container) restore.

Any pointers on purging the snap version and getting the apt version? Anyone else tried this migration and knows of the pitfalls or issues?

Huge thanks.