I use the docker container. Though I need to figure out a way to do this without exposing my home IP address.
If you would like to self-host your own Simplex Chat private relay server follow the guide here - https://simplex.chat/docs/server.html
Discussion
Yep that’s the tricky part. I think a private VPN that forwards ports or maybe a mesh network that others can join. The barrier in the latter would be the users having to join the mesh network to be able to connect.