Typically people actually go the opposite direction and move out of snap because they out grow it.
If you have a small server snap is still of course a good choice.
Moving from bundle to snap would go something like this:
mongodump --db rocketchat -o dump
tar -zcvf backup.tar.gz dump
Of course sub rocketchat with the name you used for your database.
Move the backup.tar.gz to the server running the snap.
Then the snap restore steps listed here: https://rocket.chat/docs/installation/manual-installation/ubuntu/snaps/#how-do-i-restore-backup-data-to-my-snap
