correction, thats 2' from the wood fence.

Honestly... not enough sun, not enough space, and I wonder if you need a pollinator... or is Dorsett self-pollinating? Could you possibly move to any wider space with more sun? I suppose it is worth a shot but I wouldn't get my hopes up much that it will be fruitful.

Use a dwarfing (say M26) rootstock and train it up and develop fruiting wood where there is sun. Manage it like a tall espalier and I think it will work just fine.

Roots may tear up the concret wall

What direction is it facing? If south, it may do all right.

Time will tell, south or west better than north or east facing. You have nothing to lose...good luck. Maybe slow going until it clears fence...

Yes,..you can let it grow up and share fruits above the fence with your neighbors, take off bottom 4 branches now, then more in a couple of years.

The tree is facing east. I have a 30' row of 6 apple trees along that block wall, spaced out 5' apart. The tree shown is the closest to the house/backyard fence. I plan on removing the fence boards and replacing with gavonized wire to prevent my dog from leaving the side yard, but still allow sun to get in. This should give me a little more sun during spring & fall when the sun will be coming from the south (opposite side of wood fence.)