How about some wild edibles?
Viburnum edule [url=https://plants.usda.gov/java/profile?symbol=VIED]ONLY grows in coldest regions[/url] but is touted as the best tasting viburnum species.
Also, though not a fruit per ce, but fruit of the forest -- what about mushrooms? [url=https://www.fieldforest.net/store/index.php?main_page=page&id=7&chapter=0&zenid=b1b9ab8d1d25c6e9cfbd24e375f520b5]This supplier[/url] is based in Wisconsin and provides excellent customer support.
Again not a fruit, and maybe not practical in terms of "growing" but if I lived a little bit further north and had the room, I would definitely include Sugar Maple trees in my list of must-haves.
Have you tried [url=https://www.sln.potsdam.ny.us/]St. Lawrence Nurseries[/url]?