Seeds are available. I imported some different Stenocereus species from European sellers. Some are on eBay from US sellers, more expensive than from Europe. A small lots permit takes maybe an hour to figure out, is all online, free, and gets approved instantly. I have a lot of pruinosus seeds I collected from the fruit I bought. I can send you some Kevin.
https://www.succseed.com/en/seeds-cacti/stenocereus/https://drive.google.com/file/d/1qsuv_ikbFQ1yjJWdTYCtcRrVcSvalUWd/viewI think S. pruinosus is the most common commercially, not sure why S. queretaroensis seems to get touted more. S. stellatus is grown alongside pruinosus, Queretaroensis is more to the north. This guy has multiple videos showing pruinosus and stellatus being cultivated:
https://www.youtube.com/watch?v=RQ9UlZYJq3c (remember youtube can translate for you)
I did some research, but never really found anything about any one species having superior fruit, or better cold tolerance. There are differences with regards to growing season, one grows during the dry season and one during the wet, something like that. My theory is there are about three groups of columnar Stenocereus species, with different areas of Mexico having local species of these: stellatus-like, pruinosus-like, and queretaroensis-like. In the Puebla area, seemingly the main commercial growing area--and the area where they've been most domesticated--pruinosus and stellatus are native. To the west it's Chrysocarpus, Quevedonis, and Fricii. Not scientific, but to me Chrysocarpus looks a lot like Queretaroensis, montanus, and martineziii (grayish green, black areoles, mostly spineless with age), quevedonis looks like stellatus and treleasei (bumpy ribs, pink flowers), and fricii looks like pruinosus, griseus, laevigatus, huastecorum, and maybe chacalapensis, aragonii, fimbriatus, and eichlamii. Thurberi doesn't really fit with any. From pictures alone it can be very hard to tell them apart. I bought some "S. pruinosus" seeds collected in Queretaro state, which makes it very likely they're technically S. queretaroensis, since S. huastecorum--the local version of S. pruinosus now that it's been split into four species--doesn't grow on that side of the mountains. And queretaroensis is one of the more distinct... But look at pictures of stenocereus from that area on iNaturalist and there's discussions about whether they're actually huastecorum based on looks, but the conclusion from the experts is they have to be queretaroensis based on the side of the mountains they're on...
It also seems like mostly people grow orchards of the local species, not spreading pruinosus or stellatus clones around the country. If pruinosus/queretaroensis/whatever were significantly better, I'd think they'd be growing those all over Mexico. There are reported to be some better ones growing in villages where the people have been selecting for the fruit to various degrees for centuries, and the big orchards (mainly in Puebla state?) have some selected clones they're growing. I think these are mainly pruinosus and stellatus.
I've started seeds of around a dozen types. Very slow growing so far, but I bought a S. huastecorum (?) around two feet tall, and it's put on maybe six inches since I bought it this spring. And it hasn't even been a that warm this summer. S. pruinosus is reported to be a fast-growing rootstock.
http://www.kadasgardens.com/Cgraftingstocks.htmlThe guy at the nursery recommended Pachycereus hollianus for fruit, so I got one of those too. He seemed lukewarm on Peruvian Apple Cactus for fruit. Trichocereus 'Flying Saucer' is said to have very good fruit, and would probably would be better for my climate.
Also worth mentioning, in my research I found some reports of Stellatus growing really well in New Orleans.