I do not know what the fruit was.
I think connected to this story is this fact;
she shall be called Woman, because she was taken out of Man. Gen 2:23
The woman is the help meet for the man and she was taken from him.
Help meet the Hebrew word `ezer which means helper.
It was through the helper (the woman) taken from the man that God by his Spirit brought his Son into the world. They called his name Jesus.
Jesus told his disciples that if he did not go away the Comforter (helper) would not come to be in them.
Titus 3:5 a bathing of regeneration, and a renewing of the Holy Spirit, Happened to Jesus is is the means by which man can again be made whole.
After Jesus received the renewing of the Holy Spirit the shed it forth on man and it will be by that Spirit mortal man will be quickened, made immortal. Rom 8:11 1 Cor 15:
All because the Son of God was born of woman.
This came about because of trespass and sin. Also lust (whatever that is) gives birth to sin.
Something went on in the garden we do not want to talk about, yet from that point on the word of God confronts us with it. We see ti with the first children. We see it before the flood. After the flood with the son Ham. I think it is related to this verse. Prov 30:20 Such [is] the way of an adulterous woman; she eateth, and wipeth her mouth, and saith, I have done no wickedness.
I do not know what the fruit was but, "she took of the fruit thereof, and did eat, and gave also unto her husband with her; and he did eat."