Let me set the right expectations. I took all the work I did to get https://cupid.careers federated and turned it into a standalone Django application. It does not yet implement C2S, but the plan is to have a generic AP server with a system to let accounts register their own actors.
I am taking a lot of inspiration from https://codeberg.org/Vocata/vocata (h/t @nik) and hope this saves the way to my idea of a "Social Web Browser".