apt-get install postgresql, connect it, and you're done.

It doesn't seem that simple. When I researched Nextcloud in the past, I avoided it because of warnings like the ones in this thread: https://news.ycombinator.com/item?id=25481465

Ctrl+F search that thread for "failure".

If Nextcloud has solved whatever issues were happening in 2020, it still doesn't necessarily instill confidence because one can remain skeptical and assume there are new issues still happening in 2023. E.g. https://github.com/nextcloud/server/issues

It's going to take some time to wade through all those Github issues to determine if there are any showstoppers that would affect one's installation. This doesn't look like a low-maintenance solution. The gp's wording of "dedicated the time" seems very relevant. Copy&paste of some YAML doesn't really address the work involved.