Hi Alec, would you mind clarifying what you need from Stem? As far as
I'm aware Stem supports v3 onion service creation...

https://trac.torproject.org/projects/tor/ticket/25124

See the 'version 3' note at the end of...

https://stem.torproject.org/api/control.html#stem.control.Controller.create_ephemeral_hidden_service

I'm unaware of the ball being in my court on any v3 Onion Service
stuff. If there's something I should have on my radar then please let
me know!