How does it work?

[axelkar]

How do you get the engineering ROM?
Can you use e.g. the EngineerMode app on stock OxygenOS?
What does the persist partition contain?
How does #14 have references to RPMB, while it's supposed to be only accessible to the TEE?
What is keybox.xml?
How can you lose the TEE attestation keys? Are they not fused into silicon?
Is this just for flashing new attestation keys, using engineer tools since the Android platform doesn't have code for this?