Zero room for advancement until it becomes so understaffed they provide you with a super low-ball salary offer that will take months for you to negotiate to even close to a standard market value for a beginner manager ($60k+ now with inflation) GMs aren't paid close to a standard market salary even after years. Out of company GM hires have consistently shown to be bad decisions with very little exceptions. Even seasoned GMs can't match up to training that hourly non-management employees provide to new locations.
Training for this position is "Don't mess up" That is it. You are thrown in the ring of fire right off the bat.