Indiana Berry offers a zone 4 pawpaw:
https://indianaberry.com/products.php?cat=7&pid=80 . They also say that
"Two varieties are needed for pollination," but they don't say if they have
two varieties.
Jim Fruth
Brambleberry Fruit Farm
4002 Davis Street
Pequot Lakes, MN 56472
1-218-831-7018 (My Cell)