“Correctly” is a big caveat. Almost no HW implementation is auditable in any way.
My baseline assumption is that even the good commercial products are only secure from a non-determined attacker, not TLAs. Anything safe from TLAs is what’s being sold only to them.
If you own an Android device, your disk encryption is most likely provided via a UFS/eMMC hardware component known as the "Inline Cryptographic Engine" (ICE). Reputable device manufacturers validate the ciphertext that these devices write out to storage in a test environment by running the plaintext through a software encryption process using the same encryption keys as the OS provides to the ICE. If the ciphertexts match, then it would be unlikely that the hardware encryption engine isn't doing its job right.
>Anything safe from TLAs is what’s being sold only to them.
I think you're overestimating how much backdoors there are in products vs actual bugs. As we've seen with with recent vulnerability disclosures, there's plenty of bugs that were put there unintentionally.