I’ve done this a few times now, and when you know how to do it, it’s a breeze.

Posting the “recipe” here, for my self and anyone who might need it.

Should be pretty self explanatory for those with a little experience with ZFS.

Obviously, after starting LXD after migrating, you should test if everything is OK before destroying the old dataset.

(you will need the packages sqlite3 and mbuffer, mbuffer can be omitted at the cost of some speed)