Here is something I read about semps...They occur from Morocco to Iran, through the mountains of Iberia, the Alps, Carpathians, Balkan mountains, Turkey, the Armenian mountains, in the northeastern part of the Sahara Desert, and the Caucasus. Their ability to store water in their thick leaves allows them to live on sunny rocks and stony places in the mountain, subalpine and alpine belts.
So you are right there is no reason you shouldn't be able to find them locally, and wild
(I didn't realize they could be found in "wild" in subalpine locations)
Like some other plants of Southern Europe, their ancestors have likely a subtropical origin. Morphologically, they are closely linked with the genera Jovibarba, Aeonium, Greenovia, Aichryson, and Monanthes, occurring mainly in Macaronesia (Azores, Canary Islands, Cape Verde, Madeira).
Seems to me they're highly adaptable and therefore able to be in full sun, or less full sun...I only know they like cold temps, they just settle in and get really full and healthy looking when its been cold, with less rain - again though, that's my personal growing situation, and there could very well be other conditions (unknown to me) which cause them to grow so well in this Pacific Northwest area. That I know of, we do not have any wild here in our mountains. Only sedums.
Hope this helps add to your considerations!