Kumquats? Pomegranate? Maybe you could train a Satsuma to be more upright, although that's not their natural form.

Fruit trees would do better with branch bending to encourage fruiting and allowi a good air flow to lessen disease issues. If the space you have in mind is less than 12', it would be hard. Fruit drop could make a mess and may cause unhappiness to the neighbor.

Jujbe fruit are not that messy by comparison, but a tree can be tall and wide and some have serious thorns.

Feijoa does well in your area; choose a young plant with upright, acutely angled branches. Evergreen and a nice spring bloom.

14 ft. is small. If you were talking about apple trees for instance this height would be considered typical of a fully dwarfed one.

I had the same thought about the fruit mess. Also I don't know that I'd want to be eating from along a frequently used vehicle access route.

I live in the same climate zone, in Oakland, and have several fruit trees, so I know that the following have a proven track record. Someone else suggested Feijoa Sellowiana, also called pineapple guava. The variety "Coolidge" grows well, fairly upright, has beautiful flowers and is self fruitful. The following 2 suggestions could work with thoughtful pruning, and love our climate, Santa Rosa plum or black mission fig. Or a dwarf Meyer lemon tree. And now is a great time to plant with the winter rains to help get the tree established. I recommend East Bay Nursery in Berkeley, they have a great selection of healthy fruit trees and a knowledgeable staff.

Pears tend to grow relatively vertical if you'll let them. In any case, no matter what fruit you choose, you will need to prune diligently and tie branches up where you want them to go.