“The lord from the Tusita heaven”: "After the Blessed One died from the Tusita heaven, he entered the womb with mind and knowledge
Maybe Bodhicitta is simply this. Mind-knowledge? But wonder how they saw it in the time Nidessa was written. Seem to be saying he was already enlightened. But not as a Buddha ofcourse.
https://zacanger.com/niddesa/assets/niddesa.html#cūlạ-niddesa