I had read quite some years ago now that Apple made use of NetBSD as a starting point each time they needed to port to a new architecture (you know how they say

I had read quite some years ago now that Apple made use of NetBSD as a starting point each time they needed to port to a new architecture (you know how they saying goes), but ultimately it's the FreeBSD userland and XNU kernel that remains... albeit very outdated userland these days - maybe that's why they don't donate much, they only have FreeBSD from >12 years ago. It's always a PITA giving bash scripts to mac users.