...aand I feel so stupid. Seeing your screenshot made me realize I was reformatting the partition, not the actual drive itself. Originally it gave me an error and when I tried again it worked, then did the cloning process, mounted the EFI with no issue, copy/paste, unplugged original drive and booted. 0 issues. It was me being dumb and messing up literally the first step.
Thank you so much pastrychef for holding my hand through this and I'm so sorry that I wasted your time (I know you first mentioned that it sounded like an initialization issue).