FOSSCOMM (Free and Open Source Software Communities Meeting) is the pan-Hellenic conference of free and open source software communities. It is addressed at programmers, students and anyone else interested in the open source movement, despite their background.
You can check their page
Nextcloud will have a booth staffed by @Pantelis and me.
We also have presentations.
and he has a workshop
The first 2 presentations will have live streaming and will be available on youtube.