Alchitry Board to Board Connectors

Here are links to another sellers. Hope it helps you.

https://cz.mouser.com/ProductDetail/474-PRT-16891
https://www.digikey.cz/cs/products/detail/sparkfun-electronics/PRT-16891/12715734?s=N4IgTCBcDaIAoCUAqBaAjANgBwE40gF0BfIA