I'm in Southern California zone 10A, and I'm getting ready to order an apple tree or trees. I did some research looking for "low chill" apple varieties. I found some like Anna and Fuji. Then I looked around a little more, and found info about Tom Spellman from Wave Wilson Nursery growing ALL KINDS of "high chill" apples in Irvine, CA zone 10.
Pretty much all of the 30+ varieties they planted worked. They all fruited in like 2 years. If I remember correctly he said the trick is to use a semi-dwarf rootstock. I think he said he was using M111. They also pruned and shaped the trees.
I'm looking at either getting like 4 columnar varieties, 3 semi dwarf varieties planted next to each-other "in one hole", or a single semi-dwarf with 5 or 6 varieties on it. The latter two methods both require careful pruning to keep them all in balance with each-other so one doesn't dominate over the others. It's good to get at least two varieties that have overlapping blooms, because even "self pollinating" varieties produce better with a pollinating partner.