i did that partially. I have a bit user subscribed to many communities. Unfortunately that is a fully manual task - currently i don’t have an automated way of doing this

Could you add a block about I2P in general?

Somehow you are describing an „email“…

Problem with you approach is, that you have an easier maintenance, but your users need an additional tool. Especially when grandparents should use this, you should stick to what is there.

In theory you could host a matrix server and install some bridges like whatsapp, discord, etc. probably you would be able to create a matrix room and invite your granny via the whatsapp integration, your friends via discord, etc.

Disclaimer: I did not set up such solution - this just came to mind for your situation.

Since a move is tracked by the „Bürgeramt“ they will find you since this is a jurisdical topic.

About ten years ago, a friend got such letter about 700€ and they argued that the wifi was public (hotspot mode) and they did not know who did that.

Besides, those are the reasons why torrents are nearly dead in Germany as far as i know.

I am not too deep into the scene, but i could imagine that this is not neccessarily desired since every signed release could be linked to them from a forensic and juristic perspective. (in the case they are arrested)