You are talking very northern climes for them to not be able to forage at all. Lower 2/3rds of the lower 48 and they should be able to forage enough. They will do better with feed but not required. You can get breeds that still have the “forage instinct” but even the modern egg producer breeds will pick up they habit if needed.
in my area one has to contend with winter and with hawks and eagles fox and coons. best that can be done is to have a herding dog and a movable forage coop that you move once or twice a day.