eh

You could represent booru tags as hashtags, and PixelFed already shows how image sharing can be done.

All that's left is someone to do the hard work of patching together a booru UI for ActivityPub. Hell, considering the use case it could be a frontend for an already existing backend-only AP software like GoToSocial. That would make the implementation drastically simpler as you wouldn't need to deal with any of the AP parts at all.

I have no idea if there was a native setting to disable it or if it was RES's doing but I completely forgot chat even existed.