I can respond here, because I’m not too keen on my funny bsky posts becoming a primary source of info for VRChat positions 
We have talked about oAuth and SSO solutions before internally. Versions of it are interesting, like allowing people to sign into other services using their VRChat account as a form of authentication. This could be cool – but it isn’t a small amount of work, and we simply don’t have it as a priority right now. So, it isn’t “never.” We just don’t have an ETA other than “maybe? sometime?”
In short, there’s no particular thing I can point at and say “this is what is making it hard/impossible”, but instead our answer is “this would be cool, but it is not something we are working on right now nor is it on our roadmap.”
Personally, I don’t see much issue with the “put this text in your bio” approach. There’s a few games that I used to play (EVE, mainly) that had groups that would do this. While janky, they were both effective and kinda cool. I don’t believe those types of systems would impinge on our current API usage guidelines or our Terms.