I figured out an email address for the Genesis executive in charge of customer satisfaction and after market sales. He said pretty definitively that work on the car may only be done by dealers currently authorized to sell the GV60. He specifically said I should wait until it's offered for sale in Maryland, which he said should be in the first quarter of 2023. I went back to my salesperson who seemed genuinely stunned that no one else could work on it and said he'd go talk to his regional manager. For me, it seems like this car needs very little routine maintenance for the first 6 months so from that perspective I'm less worried, but I have bought cars before which had defects almost immediately and that is my bigger concern.
I may have a bigger problem than you because I have outed myself to Genesis before purchasing the car. I think you are right to make Genesis deal since the car is under warranty and (I think) no one specifically told you ahead of time that you would not be able to get the car serviced in your state.