The family plans on moving from zone 7a to a 6a in ~3 years. In order to get a jump start with the pears can they be purchased now and remain potted for 3 years? Maybe in very large air pruning pots?
Varieties would be Seckel, Ayers, and Harrow sweet if it matters.
I have a pear tree purchased from FEDCO 5 years ago in a 15 gallon pot. Never did get the clearing done for it’s planting location.
I also have some Cleveland Select callery pears in pots for longer than that and not even watered except by rainfall.
So, 3 years is certainly not an issue. But if these are currently potted trees you are buying…you’ll need to transfer them to a larger pot probably before 3 years are up…or they’ll get badly root-bound.