Sure, i2p or the invisible internet project is a FOSS project which acts as an anonymous network anyone can potentially access, and host on.

It does this by creating end to end encrypted peer to peer tunnels between its users and then sending data through itself via a path between some of the 50,000+ volunteers that make up the project. The path data takes is random so a third party seeing any communication in full is highly unlikely, and even at that, its still encrypted.

The software that implements this is the i2p router, and when using the i2p router you become a node on the network like everyone else using it, allowing pieces of anyone's data to move through your router, just as your data moves through theirs.

The UX/UI is very good for new users and makes it easy to access, or host. Particularly, to my understanding, i2p is also very popular for torrenting due to the nature of how it works (in comparison to similar projects such as tor, there is an entire built in solution for torrenting included with i2p).