TL;DR: It is completely doable, and we’ll be adding support soon!
Solid uses OIDC (OpenID Connect) for user authentication. OpenID Connect is a simple identity layer on top of the OAuth 2.0 protocol, and is widely supported. As a result, you’re going to start seeing “Login with Solid” here, and in many other places as well very soon!
While Discourse (the software that powers this forum) supports OAuth 2.0 out of the box, they didn’t include OIDC. That said, there are several projects on Github that have added OIDC support for Discourse that we’re looking at.