The fact that we have to call it "their firmware and secure enclaves" is a bit telling, though. The majority of consumer-facing devices today have a layer of inscrutability that we leave up to the manufacturer to implement properly. For instance, Microsoft has Bitlocker, but I couldn't confidently say that isn't backdoored either.

Apple has whitepapers, but they're about as verifiable as LK-99 in-practice. Their security model entirely revolves around the Apple-issued root of trust, and if you can't trust them then you have to hit the bricks. If you don't own both ends, the end-to-end encryption shtick is a theatrical farce.