nice that you can mark your own post as solution (which it is. thanks for that).
now taking it a little further (and maybe OT in a strict definition of the topic) …
is there a common strategy how to handle a growing /var/snap/nextcoud/ folder efficiently?
I mean where do others move that to. Do you put the entire /var/ away from your (maybe small) system drive, or only /var/snap/ or …
I guess you could try two ways - create a large filesystem on another disk (or elsewhere), integrate it into Nextcloud using the external storage app and move the content there, which is how I manage my 42TB storage array whilst keeping it available via other means (CIFs, SFTP, etc):
… or potentially also “move” your data dir:
“Move” because you’d be symlinking from the existing to new location. Pretty sure that’s supported with the snap install.