Welcome to the forum! Here’s the page where you can join the project if you’re interested, and here’s the list of grafted varieties.
At this point there are no varieties that I’d recommend outdoors here, unless you’ll be covering them for our worst freezes. The goal of the project is to plant thousands of seedlings in the hope that some could maybe survive in our climate.
It’s too early to really draw any conclusions yet as to greenhouse varieties, either, as the greenhouse trees didn’t set any fruit last year. Hopefully some fruit will set this year, with about twice as much biomass and a couple varieties flowering that didn’t flower previously. But if not, then there may be issues with the overnight lows during flowering, which can impede pollen tube formation and embryo development.