Things we know for fruiting faster: Qunice rootstock (or OHxF87 if too cold for quince), Harrow Sweet pears, don’t prune or prune only the very smallest amount. In the second year, bend branches below horizontal. MAKE SURE TREE IS STAKED and branches are supported.
I would love to hear from others if there are other pears known to be especially precocious. For me, Dutchess was very quick to develop fruiting spurs and flowers (but I pulled the flowers off so have no idea if it would have actually developed fruit). Sekel, Douglas, and Dana Hovey followed a year later (but I also pulled the flowers off these).
For pruning:
Pears don’t really like open vase very much… Here’s a picture of what might happen: How do I prune this pear tree?
I would try modified central leader like @Auburn . Growing in a pot will help keep it small. I don’t know much about growing in pots - but I know people do!
That said, I’m not sure how modified central leader would work with a different variety on each of those branches. It looks like there are 5-6 coming out of a very short piece of trunk? that makes me worried that if those branches get loaded they will split.
I don’t actually know what would work in your situation but here are some ideas:
- Get some more rootstock and espalier to the fence with 1-2 varieties per plant. If you can’t do the fence, then you can put a rebar or similar structure that gets put in the ground.
- Pick one of those varieties on the tree and let it become the central leader. Pick one that is most fireblight resistant and vigorous. As it develops scaffolds, move the grafted varieties to the scaffolds.