I want to see teams take a #Matrix app and try to implement #ActivityPub in it, using and taking notes for any FEPs necessary on top of the AP spec. Or, conversely, take an ActivityPub app and try to implement Matrix in it.

In each case, I don't mean adding Matrix app style features to the AP app, or vice versa. I'm talking about re-implementing the existing features using a different protocol. To see if it can be done, and how hard it is.