Seems ironic to ask this on a post where a guy's cheating device malfunctions causing him to lose. There could be limitations which prevent him from cheating completely accurately

No, not ironic at all. Said device was extremely unreliable and failed to win even 2 games - while the person you accuse of cheating has improved from 2400 to 2700 in about 2 years. Pretty reliable cheating device he had, only to fail at the crucial moment.

Also, consider this: Nakamura knows that the position is good, but does he know it before he sees the evaluation, or after? Because it is a fact that when top player knows it is +3, he can explain why it is so good. But just looking at the board, without knowing the evaluation, he might have a very different conclusion.

I don't know about his game yesterday with Firouzja, but the rumor is that Magnus thinks Niemann got hold of his opening preparation before the game, which would put him at a huge advantage.

This is not the point. The point was that he good enough to nearly beat the #4 in the world if he wasn't cheating.

Everyone has their good days and bad days. Elo rating estimates a probability of an outcome, and even with 2880/2680 it is far from zero.