"Remember Internet forums? Those bustling online spaces where people gathered to chat, share ideas, and build communities? While social media giants like Facebook and X (formerly Twitter) took center stage, forums continued to thrive. Now, one of the leading open-source forum software providers, NodeBB, is joining the fediverse. Starting with NodeBB v4.0.0, federation is a core feature": Opensource Forum Software NodeBB Joins the Fediverse - OSTechNix https://ostechnix.com/nodebb-joins-fediverse/
Scienceforms (https://www.scienceforums.net/) is still up and being used, unlike social media there are posts and discussions on there from at least 10 years ago that can be read and still replied to. This is great as it means I can find old questions and it means people are in theory not asking the same questions. They can search or be directed to the original post.
I am not sure what back end it uses. It would be interesting to see if they would be able to federate.