Ah gotcha didn't think of disconnecting from split screen. Hopefully PS5 will let me choose that the same account is using the second controller as the assist controller when I reconnect it. I'm definitely for full screen gameplay. Thanks!
I gotta say, for a company that's gotten such praises for listening to player feedback, the lack of simple options like "create a single player campaign with multiple custom characters" or "make dynamic split screen" or "allow camera inversion" and them not even acknowledging it is just baffling.