Today, US based file sync & share vendor Kiteworks announced their acquisition of ownCloud and Dracoon. Nextcloud offers a free hands on migration service and takes over the remaining runtime of the contracts. Migration is a very quick and easy process, as shown by the many hundreds that have done this already over the last years.
It is definitely faster on Postgres. I prefer MariaDB for ease of administration, but NC definitely benefits from postgres. Also, redis helps out a lot.
If you aren’t on the AIO container, seriously consider it. It seems like that’s the way they’re going, and there’s facility for addons (https://github.com/nextcloud/all-in-one/tree/main/community-containers) that you can enable. I’ve put in a request for PGAdmin to be made a part of the community containers. I would do a PR and maintain that but I’m not familiar enough with their plugin setup to risk it.