For example, North Dakota is the smallest state with a public R1 university, and the smallest with a credible one is Hawaii (UH-Manoa)

It's a good point. Wyoming has a population of 580K, PEI of 180K. There is probably a practical critical mass for statehood; I'm not sure what it is. There are various things a state must do, and small states just run out of resources.

PEI? But aside from that...