I don't know if this helps but I know it can grow it Portland and urban areas of Seattle, although it doesn't grow so well. That would be zone 8b.
You might be interested in this blog. She planted a small loquat plant in Gloucester, Massachusetts. It died to the ground over the Winter so she decided to dig it up and replant it in a spot more sheltered from the wind. To her surprise it kept growing and got big. It hasn't born fruit.
https://goingtoseedinzone5.com/2009/08/24/a-loquat-in-zone-7/Someone in zone 7b Alabama wrote that they had several loquats and that they had been doing great, but that climate zone has more heat and a longer growing season than more northerly zone 7 areas.
Someone in the U.K. observed that loquats typically begin fruiting in the seventh year. Someone else in Vancouver, Canada, said they had a loquat tree in the ground for 5 years, it was 6 feet tall, but it hadn't produced fruit yet.
Loquat trees typically bloom in late fall or winter, so the general consensus seems to be if you are in a colder climate not to expect fruit.
Someone else in zone 8b Alabama commented that when the Winter temperature went down to 19F one year none of fruits survived, but the leaves were not damaged.
Some people just want to grow loquat to be able to know what the fresh fruits taste like. In my opinion, the taste is nothing really all that exotic or wonderful. Compared to a good apple variety fresh off the tree you're not really missing anything. (Although the flavor is not really the same as apple)