Hey there! When it comes to tabletop OCs, we've landed on allowing people to app OCs from their own personal campaigns, but not from other people's campaigns that have essentially been elevated into canons in their own right. So you could app an OC from a game you've played (or you could use an open-source tabletop world as the basis for your OC's world), but you couldn't, say, app an OC from the universe of Critical Role or The Adventure Zone.