☒ have you seen their docs on this? https://fullcalendar.io/docs/google-calendar It looks to be fairly applicable to what you're asking and also has fairly minor changes from what this episode covers.
I would probably start with their event docs. I would probably also use a stimulus controller to wrap select2 and do the logic within there. Sounds like a good follow up episode. https://select2.org/programmatic-control/events
☒ I would probably look into the redirect_to_finish_wizard method and redirect the user to a business steps controller which "repeats" the process but for the business domain. So, first gather the information about the user in the user steps controller and then redirect to the business steps controller where you can then gather that information.
