I don't think this is related. This is just public key verification, the kind that other E2E messaging apps already had. I don't know about the specifics but as I understand, Beeper Mini could implement this too if they want to.
Theoretically the two are orthogonal. There's no reason why Beeper wouldn't be able to implement contact key verification; there's no hardware attestation component to it, as far as I can tell.
Practically, the added complexity of having to integrate with iCloud Keychain certainly won't help.
I use Linuxbrew extensively across multiple WSL distros every day. As the “weird Windows person” on a team full of Mac users the experience is pretty uniform—the same brew commands for standing up a macOS dev environment mostly “just work” on WSL/Linux.