Ive been using Yggdrasil to connect my devices. Unfortunately this doesnt autoconnect wifi, and doesnt have an IM app built for it. It does however allow you to use pretty much anything that uses a direct IPv6 connection, so its really useful to be able to ssh into my devices nearly whenever. Lately Ive been looking at Reticulum and the LXMF protocol built on top of it. I mostly just tried the Android Sideband app, but ran into battery usage issues.