New setup strategy advise needed

For option 2, you would create an app that uploads via webdav? Like the anonymous upload via browser which was introduced in NC 10:
https://docs.nextcloud.com/server/10/user_manual/files/file_drop.html

I also found a feature request for an client-side application:

It hasn’t been requested for mobile devices yet. @ios @Andy @tobiasKaminsky