I don’t know if this is a good idea (after all Inclusion & Diversity should be the norm), but want to discuss with you about it.
So any community and fedi instance where people interact needs a Code of Conduct, right? This is usually a rather long document that specifies very clearly the rules one must obey to when participating. Among those are ones about Inclusion and Diversity. This formal document is needed to point to if someone misbehavess, and to take action as needed.
But still narrow-minded and abrasive folks end up in these communities, not having read the CoC or just not caring about it. As an extra discouragement to their bad behavior, and hopefully get fewer of them to join in the first place, we might design a badge that expresses Inclusion & Diversity as the CoC intends it to be and which any community can show prominently in their channels. The badge can link to the CoC.
(I think I will add this idea for consideration in the Social Coding Movement I am involved with, and preparing for launch)