It's close enough, because (most of) the encryption keys are wiped from memory every time the device is locked, and this action makes the secure enclave require PIN authentication to release them again.

> It's close enough

Not really, because tools like Cellbrite are more limited with BFU, hence the manual informing LEO to keep (locked) devices charged, amd the countermeasures being iOS forcefully rebooting devices that have been locked for too long.