@christian @Suiseiseki You have to do it within the program itself (according to the strict AGPL interpretation, you have to offer the source code as the very first thing when any user accesses the program running on your server). And no, NextCloud does not do this, and neither does any other AGPL program I've come across – it's a mess.
marcan had a great twitter thread on this (with a bunch of examples), but it's unfortunately gone.