Doubts over the second principle of Monothelitism

[buzuxi02]

I have a related question:

How could Adam and Eve, with their pre-fall human wills, sin? They didn’t have gnomic wills yet.

Was it due to the fact that they were still creatures who were yet to receive glory if they chose not to sin? Was the reason Christ can’t sin because He Himself is Divine (in addition to possessing a human non-gnomic will)?

There is no pre or post fallen human will. It's the same. Adam and Eve still were capable of gnomic willing, the only difference was before the fall Adam and Eve were naive like babes.
Christ being perfect God and perfect man had no gnomic will as he has perfect knowledge.