Not only France but Europe does it pretty commonly to plant things that attract birds and wildlife as well as providing a natural fence. If you have ever watched Clarkson’s Farm he does it on his farm. So do you want a wildlife fence? or a personal hedge? I think in some circles they call the personal hedge a Fedge (fruting hedge).
To answer your question there are some cultivars that you can virtually walk away from as they need very little attention.
Healthberry- Clark’s Heirloom blackberry- 39th parallel nursery coined a good term in that its like a Little Shop of Horrors. He also said that it is clear evidence of Permaculture. A term that hasnt been used is that its invasive… i dont want that to be a negative trait but Himalayan blackberry is also invasive. I have tried to trellis this but it doesnt want to be trellised. My canes that were treated with care became the size of small baseball bats…and signals were sent to send up new canes 10 to 20 feet from its crown… Berries were fairly small but tasty. I gave up trying to tame it…it is now free to live out its life trying to take over.
Wineberry- is also ‘invasive’ but i think at this point with them selling them in stores it is also almost native. Very worth growing for yourself and wildlife.
Himalayan- I am growing it and have found it growing wild in my state in many places. Its a very adaptive plant that needs no attention at all and will grow in ditches or hillsides full of trash and rocks. I found a thicket of them a few years ago that was probably several acres… so at this point i think they are native. Nice sized tasty berries that are much better than the tiny wild ones that are technically invasive but are considered to be native.
Ebony King- is one of the few that needs very little to no attention and is a very worthy plant of growing I have posted pics of canes 15 feet or so long that the person got over 1000 berries off of one plant.
Highly bred cultivars do not seem to have the same ability to self sustain without eventual self destruction by disease etc. At least from what i have seen.
From what i can tell Amethyst purple would be a great addition to that hedge… it may be more vigorous than Triple Crown. Canes are extremely thick and strong enough to support any crop in its 2nd year.
Cumberland black rasp would probably fit in nicely. Its been around for over 100 yrs…
Hazelnuts- im growing several varieties but have planted the most Hazelberts. I got mine from Jesse on here and they are doing well.
YMMV but any hedge or fence like that here encourages wildlife…it does not form any kind of fence per se… my local deer munch on multiflora rose and thorns are part of their diet. My local deer prune all of my wild blackberries and raspberries in early spring which encourages laterals which in turn helps the plant. The birds and other wildlife disperse the seeds and create their own habitats.
I grow lots of things for nature to offset their desire to eat my cultivars. Such things like native elderberries have small berries that they prefer over larger berries like Marge.
As for hazelnuts- its hard to outharvest chipmunks. This in turn brings out my owls and birds of prey which keep things in check.
Is a hedge possible? yes… but you will either have to share or be very diligent in harvesting… it is a dinner bell for nature.
only hardy to z5 but the last 3 winters have been z6 . canes are flexible so i i was able to cover them for protection. got the tips of 2 of them buried to expand the patch. how productive and how big are the berries?