The experimental farm network has them for sale - apparently they'll be available March-April.

https://store.experimentalfarmnetwork.org/products/monkey-pu...

There are some massive examples in Seattle. They are hard to miss and very peculiar. I believe they are an import from the west coast of South America: https://en.m.wikipedia.org/wiki/Araucaria_araucana

3-4 decades to maturity, before you can harvest seeds, and it looks like you need male and female plants to cause seeding - I wonder if that can be gamed by grafting from mature trees, or artificial hormone sprays?

3-5 cm pine nuts sound awesome, though. 50m tall trees with giant cones and tasty nuts that can live a thousand years - a grove of these on a farm seems like a cool legacy investment, with little chance of becoming invasive or problematic.

Not trying to be facetious. but maybe look out for monkey puzzle trees in your area? If you're in the PNW, there a few around: https://www.monumentaltrees.com/en/usa-araucariaaraucana/

The monkey puzzle tree or araucaria can be found in southern Argentina and southern Chile. The nuts are locally known as "piñon" (singular) / "piñones" (plural).

It is not my favourite nut I must say, but the flavor is OK.

Do keep in mind that these are very large trees and the leaves(needles) are very prickly to deal with. It takes a long time for them to mature and I have heard people in Seattle say that they never produce cones here.

There are several in our neighborhood, including our neighbor, but the homeowners obviously have no idea how large those trees will get based on where they are planted.

They're found virtually everywhere in Florida.

Might be hard to find considering they're endangered