I finally released a new version of the Nextcloud charm just now after upgrading my own system.
A fresh deploy drops you in on version 220.127.116.11 at which point you can use the web gui for future upgrades.
The new version (Rev: 4) supports juju storage. This allows you to have the Nextcloud primary storage separated from the Nextcloud installation. There are also a few more examples in the documentation on how to test Nextcloud on a single server with postgresql charm.
It is known to work on MAAS and AWS at the moment, but chances are that it works on other clouds aswell, like lxd etc.
For the next version, I’ll be addressing scaling of Nextcloud. If you like to help out, give me a shout.