Might be worth just checking the issue list of the documentation:
and even some pull requests:
https://github.com/nextcloud/documentation/pulls?q=is%3Apr+is%3Aopen+label%3A"manual%3A+developer"
Even here on the forum, if you have to wait 6 month for a response (\OC_User::getDisplayName($userId) deprecated/ remove), missed follow up answers (Nextcloud Event Debugging), no answer (Change user language from app controller).
If the documentation is great and there is some timely feedback on development questions, you will at least not discourage interested developers.