Not unless this species is pretty unique!! Blackberries grow extremely easily from seed. They just need to be planted in fall so they can go through proper natural stratification. Even berries left on the soil surface can germinate and form new plants. Second year plants from seed will even bear fruit.

Try checking with any native plant nurseries (or your DNR) for starts if seeds are difficult to locate.

From the US Forest Service:
Seed: Most blackberries produce good seed crops nearly every year [4]........
Germination: Blackberry seeds have a hard impermeable coat and dormant embryo [2,14]; consequently, germination is often slow. Most blackberries require, as a minimum, warm stratification at 68 to 86 degrees F (20 to 30 degrees C) for 90 days, followed by cold stratification at 36 to 41 degrees F (2 to 5 degrees C) for an additional 90 days [2]. These conditions are frequently encountered naturally, as seeds mature in summer and remain in the soil throughout the cold winter months

Scarification may help to speed up or improve germination but it is not a requirement.

The University of Washington has done propagation studies on our native blackberry, Rubus ursinus. The seeds were collected from ripe fruit, dried and refrigerated for 3 months. They were then surface sown, watered and germinated 14 days later with a 50% germination rate. No scarification and 14 days doesn't sound like a very long germination period to me.

This is by far not the most efficient means of propagation of any rubus species and I'd suggest the OP attempt to locate started plants. Or, with permission, take tip cuttings of existing plants in spring.

Sounds like you would only grow the Prime Arks for their primocane crops due to your harsh winters. I may have mentioned this before, but I would figure out how many frost free days you have before you plant the Prime Arks. I have about 180 days which gives me about 45 to 60 days to harvest the berries before frost. That assumes the Freedoms are one the same fruiting schedule.

I can try to find out the minimum growth period for Prime Ark Freedom but if it is similar to Prime Ark 45, then you may want to limit your purchase to 'trial' plants. If I back out the 60 days for fruiting from the total frost free days in my area (180) then we are looking at 130-135 days for the plants to begin fruiting (about 4.3 months). You would need at least that many frost-free days to get a crop.

You may be able to speed that process by warming the ground over the plants by using black landscape fabric or similar material or by covering the fruiting plants when you reach frost periods in the Fall.

Going a completely different direction, you may have more luck with less cold hardy trailing blackberries which you can cover more easily. If you have a long period of snow cover, the better insulated the trailing blackberries would be. There is at least one person I know of that grows trailing blackberries in Alaska but he has a lot fewer frost free days to work with.

Northwoods. I grow a number of trailing blackberries. many are not hardy here, but covering them with leaves and using anti-desiccant sprays can help them survive. I need more time for experimentation to find best method. So far I can make them survive at least. Yield is low, I hope to have better results next spring. It's a lot of work, and such. Anyway your idea of growing wild is a good one, it will work if you can find seed, Also what gardengal suggests just putting them out there could work. I have never seen it, but something here may be prevending germination. All gardening is local. I really do think though people should not give advice on techniques they themselves have never tried. That is a huge red flag in my book.

Years ago I noticed people picking native blackberries in
western WI around the town of Amery while visiting a friend. Lots of folks out with 5 quart pails picking.

My friend had already picked and his wife had a blackberry pie for me. Mighty nice.

The native blackberries seemed thick as fleas is that area,
yet I have not found them to any extent in SE WI.

When I lived in Eastern Minnesota, I found them to be plentiful too. I always wondered why nobody offered the
native strain or perhaps would use them in breeding purposes to come up with some super hardy blackberries for WI and other similar climates.

Yes they were picking along the roadsides. Also along any power lines thru the wooded areas as those spots were clear cut for the lines so lots of sunlight and lots of blackberries.

Sorry not to be more definite, but my friend moved to Spooner after that. I do recall it was outside of Amery as we were heading to a lake to do some fishing. People everywhere with their pails. Even saw some who parked their motorcycles and joined the foray to just eat them fresh on the spot.

I could not figure out what they were picking but my friend mentioned it was blackberries as his family had just picked the day before.

The issue will be to find some and dug them when dormant? Wish I could be more helpful. Good luck.

My friend worked at the Soil Conservation District but then was transferred to the office in Spooner, WI. Just a possibility, but try contacting someone at the soil conservation office for the Amery area or for your local area. Those workers put on a lot of miles walking the local
fields and know their areas well. I would think they could give you directions to a local wild stand. Or try a local
DNR office.