I proposed an investment up to 200,000 € to accomplish this earlier, but there were no takers. Actually, @erlend_sh made a proposal on the behalf of the Discourse team, which was accepted by the NGI Zero consortium. Then he left the company and the proposal was left dangling for some time until @rishabh took it over, and there was a new enthusiasm. But then the application was dropped entirely.
The offer still stands. If you’re interested in picking this up, I suggest to pursue the discussion on the SocialHub – it can be developed as a plugin. If you need any additional information about the grant, you can contact me there. See also ActivityPub Implementation for Discourse