Hi there, I wonder if that could be done. I’m using Drupal in my own domain (and server) and Discourse at subdomain.
I checked DiscourseConnect but it works in reverse side. I have users registered in Discourse and I want to keep the logins from a Discourse group into a new private blog section at Drupal 8 (with plans to update soon to D9).
I really don’t know how much it could cost but you can give a price quotation and I can analyze it.