If you end up going with conduit, I would instead use conduwuit. More development effort and better docs IMO. I think maybe even one of the main devs from conduit moved over to conduwuit? But not 100% sure
https://conduwuit.puppyirl.gay/
The domain choice? Eh, not what I would have gone with but to each their own lol
I’m pretty sure it’s a lot easier than all of that. Account settings -> oauth -> link to oauth. That’s it. Maybe gets more complicated but sounds like that should be it for your use case.