Replace breaker with AFCI

Hello I'm looking to replace 2nd breaker down on left with an AFCI breaker. That circuit is routed through a Generac load switch (2nd photo) where I'm assuming the neutral is. To install an AFCI do I fish the neutral from the load switch into the panel? And 2nd super basic question - how the heck do I open the load switch to access the wiring? 🤣 Thanks!