Retroshare is useful and somehow forgotten file sharing and communication program. It has pros and cons, but I would say it might be a good option for a small network of friends. It can also be configured to rout traffic over Tor or I2P

I think it fulfills PG requirements and might be included or mention as an option for specific use case

Ok, I get it has pros and cons, but as mentioned, there are some use cases for it. If I want to share some files with a smaller group of trustworthy people (friends and family), this might be much easier than setting up a home server (e.g. Nextcloud).

Yeah, but it is not private as the blog I shared stated. Everyone can see your IP.