I am in Dallas a zone 8 or maybe 7 area now. I have both a store bought that I believe to be Golden Delicous and either a root stock or seed grown in the same hole they both put on a few fruits. Originally the main tree (Golden) I thought was gone... i had chlorine tabs in a bucket with super clean water and thought it was just water.. so after some months i put gala seeds in the hole... I ended up with a gorgeous double fruit tree ... they haven't made alot of fruits yet, Dorsett would probably do better since it requires less chill hours but our climate has turned cooler over the winter and the summers have been staying below 100... the Gala type which may be my own "Improved Gala" produced only 1 apple the first year and then a few grew on both types this past year... I think some of it is blossom timing if i had another pollinator they might produce more...
I read that root stocks that go dormant sooner improve cold hardiness but I think most or all apples are cold hardy enough for here we just cant get production usually on the higher chill types and all apples need a pollinator... another one, a 5 in one tree I've had for probably a decade or longer has never bloomed at all! So maybe look into chill hour reqs there are maybe a few more low chill types and if you have 'lower' chill type you might have a chance to breed a new type in the years with enough chill. There are several types that only require around 400-600 and many at the 800 mark it just could take a few years longer for them to start blooming...
pears on the other hand you can pull off easier it's hard to beat a well ripened Kieffer and they seem to self pollinate well @ bumper crops almost every year while most pear types need a properly timed pollinator... I spent years picking them too early btw you should wait until they begin color change all the way to yellow, and then pick they dont ripen completely on the tree.. the grit turns to sugar spots when kieffer pears are ripened at room temp in groups... but I'm going to chance the Ambrosias if not for fruit quality, to have columnar pollinators growing around my established trees