Seeking suggestions for managing user Authentication between Nextcloud and other services

What would be the best practice here?

To allow Nextcloud users to access other local services such as Moodle, DokuWiki, Kanboard, etc.

Would appreciate input from someone who has experience managing account credentials in a successful + secure manner that allows existing Nextcloud accounts to connect with other selfhosted services such as DokuWiki and Kanboard.

Continuing the discussion from Anyone got DokuWiki integrated with Nextcloud?: