>Lots more devices are safe BFU than just Apple's. It's not that complicated on a technical level - it's basically full-disk encryption.
That's not the full story. Using LUKS encryption on your linux laptop might make it "safe BFU", but only if you're using a high entropy password. Most people don't want to enter a 24 character password to unlock their phone, so Apple/Google have to add dedicated security hardware to resist bruteforce attempts, hence the vulnerabilities.
True but those chips also exist for PCs. Some USB security keys have this feature.
Do they actually implement anti-bruteforce protections though? Or does it just provide a static secret? Moreover how strong are the anti-bruteforce protections? Do they restrict attempts to a few per second, or actually keep track of how many wrong attempts and wipe themselves if that's exceeded?
There are many different ones.