It is possible that I might be able to access this cultivar here in the area of Poland, where I just moved to. Looks like that cultivar is found here:
https://ogrodkroton.pl/produkt/leszczyna-purpurowa-corylus-maxima-purpurea
We are in the process of acquiring an unproductive organic hazelnut orchard, which is a mono-crop of hundreds of hazels of a single variety that I have yet to get a positive ID on. Supposedly its a smaller variety commonly used for chocolates, so not likely
Corylus maxima var. purpurea.
But my family also has a few other varieties growing in their backyard garden environments - one of which is supposedly a more rare and special cultivar with more red leaves. I did a quick google search to compare images of
Corylus maxima var. purpurea to what i remember the foliage looking like from a couple of trees in our garden, and Im thinking that there is a chance that they could be it!
Ill need time to confirm as the foliage comes back and nuts are produced. Hopefully by that point you will find your source, but if you don't ill be willing to share the seed - as long as there are no issues with mailing them, and if you don't mind getting variability as a result of planting seeds.
I could also try to propagate more true to type plants by ground layering, but again Im not sure what the difficulty will be of sharing over seas.