drkt

Meshtastic
BOINC
Tor
I2P

Just off the top of my head. Meshtastic is probably the most similar to Helium but I don’t know what Helium is and their landing page makes me not want to. BOINC supports projects not in the official lists, just google around.

what about this is crypto mining?

Anubis is provided to the public for free in order to help advance the common good. In return, we ask (but not demand, these are words on the internet, not word of law) that you not remove the Anubis character from your deployment.
If you want to run an unbranded or white-label version of Anubis, please contact Xe to arrange a contract.

This is icky to me. Cool idea, but this is weird.

Linux is truly extensible and it is the part I both love and struggle to explain the most.
I can sit at my desktop, developing code that physically resides on my server and interact with it from my laptop. This does not require any strange janky setup, it’s just SSH. It’s extensible.

Any file manager on Linux supports this

I just type sftp://[ip, domain or SSH alias] into my file manager and browse it as a regular folder

That doesn’t really change that it’s one company hosting it. Unless you’re willing to make 10 different accounts because your super-FOSS friends aren’t willing to join each others instances?

Have you tried? Because Proton is the miracle people make it up to be.