I grow Project Tree Collard's purple tree collard both in Laguna Beach and Fallbrook. I planted the cutting in Fallbrook out in full sun and it's taken 100+ degrees. It does not grow as much during summer and the leaves taste stronger, but fine for cooking and making kale chips. They grow well during fall and winter, at that time during winter rains, the leaves are very tender and even the larger leaves and stems taste good raw. The color is a deeper purple as well.
My only complaint about the plant is the way it grows and it needs to be staked. Staked it grows tall with a long stem and leaves are mostly at the top of the plant. If you let it sprawl it will grow more side shoots but it still needs support to keep the leaves up. At my home garden I've been just letting it meander and get support from other plants growing around it. Plant is several years old.
I also like the purple tree collard sold by Wendiland
https://wendiland.com/collections/herbs-plants/products/tree-collard-ruffleIt has a better growth habit, sturdier stems and it's more compact. The taste is good with a different flavor from the regular purple tree collard and once you have the plant it can also be propagated by cuttings. I think it was selected from a garden in Las Vegas, it has grown fine in full sun in Fallbrook all summer.
I have my own perennial kale breeding project I have been working on for over a decade. Hope to share that in the future.
Janet