Well, usually Joan won't be able to push buttons. You will need a Specialist (Chain of Command, Doctor, Engineer, Forward Observer, Hacker, Specialist Operative) to do that for you. Preferably one matched to the mission (for the bonuses specific to one type most missions award). You use Joan to get to things that your Jotum can't deal with in too close.
i mean, they are also good AROs, play well into PanOs specfire game, and in the pathfinders case has one of the best specialist toolkits in the game. But gotta take dem jabs