Yep! To add, Apple details this in their security whitepaper.
It used to be, years ago, that the limit was a purely software function. For many years this limit has been enforced in firmware/hardware.
The paths between memory, storage, and CPU are now protected by the Secure Enclave hardware which is responsible for enforcing passcode entry attempt limits. These limits can only be configured after a mandatory passcode prompt (or via MDM).
It is certainly possible that certain elements of the U.S. government have developed more advanced exploits beyond what GreyKey could have done, that they aren’t going to publicize.