Cool 😎 Anything developed fro FreeBSD can be ported to Linux if needed.
Unfortunately improvements made on Linux can't be ported back.
This is due to the license terms, But this is also the reason IBM, Google and many others have to contribute back to Linux, and Apple doesn't to FreeBSD.
Apple doesn't use that much of FreeBSD, and what they use hasn't been updated in ages.
And I don't think there's much sense porting FreeBSD device drivers to Linux, I think they are different enough. And the article is about things most important for device drivers and other kernel-level things.
MacOS and iOS have Freebsd inside their kernel. The reason it doesn't appear to have been updated in ages is the problem listed by the OP: The BSD license meant that Apple could take without ever giving back. Which is what they did.
Very happy to read that, but honestly, when reading "$1 million USD" as investment sum, it reads more like an advertisement stunt than a real investment. (Like, 2 senior developers for one year?)
We need more diversity in Open Source operating systems for desktops, laptops and any of the *BSDs is a great candidate. (Would love to see Haiku getting some sponsorship or even ReactOS!)