It could be the case that I simply do not find the right place to look for an option which is already there …
I thought about using Joplin in a team, which could be achieved if all team members share the same remote instance (e.g. a folder in Nextcloud shared between team members - and all local Joplin installations sync into it).
But: If I do this I cannot use a personal Joplin anymore.
Idea: Make it possible to start Joplin with an option like
.joplin/Joplin.AppImage --sync="https://my.own.cloud/Joplin" --user="me" --password="secret1"
.joplin/Joplin.AppImage --sync="https://my.teams.cloud/Joplin" --user="teammate-me" --password="secret2"
to easily switch between two instances of Joplin - or maybe even use them side by side.
Please let me now if I am totally nuts - and thank you in advance!