You want to do a PhD or MD/PhD? then you are looking at a career in research. You are at the very beginning of making a reputation. Don’t start by doing anything less than 100% honorable. It’s a much smaller world than you realize.
You mean transfer to another university and fly back to your old one once a month from one of the coasts? NO. You may be believing that it is “your” grant- but it is not. It belongs to the PI and by extension to the university. That you did 90% of the work is 100% irrelevant- and a fact that you need to get used to if you are going to build a career in research.
Think of PIs as the conductor of the orchestra, and you as player. You have done really well to get your seat, but you are at best in the second row of the violin section. If you leave, somebody else will do the work (and they will find somebody, even if they have to borrow them from another department).
From your posts you are still smarting over your rejections from last year, and just accepted UMi as a stop-gap, planning to transfer before you even started. Do what you need to do but 1) be honest with your PI from right now- they have a legitimate expectation that you are on-board for this project and 2) if your PI is not writing an LOR do not claim the grant.