Who is Gandabba?

I found MN38 is one of the hardest Sutta to understand.

First it refute the Sati’s ideas as wrong.

Now on that occasion a pernicious view had arisen in a bhikkhu named Sāti, son of a fisherman, thus: “As I understand the Dhamma taught by the Blessed One, it is this same consciousness that runs and wanders through the round of rebirths, not another.”>

Then go on explaining Dependent Origination.
What I do not understand is where Gandabba is fitting to Dependent origination.

“Bhikkhus, the descent of the embryo takes place through the union of three things. Here, there is the union of the mother and father, but the mother is not in season, and the gandhabba is not present—in this case no descent of an embryo takes place. Here, there is the union of the mother and father, and the mother is in season, but the gandhabba is not present—in this case too no descent of the embryo takes place. But when there is the union of the mother and father, and the mother is in season, and the gandhabba is present, through the union of these three things the descent of the embryo takes place.>

https://suttacentral.net/en/mn38

Another place you find an account of Gandhabba is MN93:
It appears Gandhabba is a Brahmanical belief.

"‘Do you know how there is the descent of an embryo?’

"‘Yes, master, we know how there is the descent of an embryo. There is the case where the mother & father have come together, the mother is fertile, and a gandhabba [the being about to be reborn] is standing present. The coming together of these three is the descent of the embryo.’

"‘But do you know for sure whether the gandhabba is a noble warrior, a brahman, a merchant, or a worker?’

"‘No, master.’>
Assalayana Sutta: With Assalayana

Ajahn Brahmali did a nice talk on that sutta. It’s on the bswa website.
From memory, he explained the gandhabba is a being waiting for human birth.

Lengthy discussion in DW.

https://dhammawheel.com/viewtopic.php?f=13&t=255&hilit=