The part where he had control of the ball with BOTH hands (yes, DB's arm was in the mix too), while he landed on one foot, fell over with his helmet hitting the ground (still no evidence of loss of control). Duel possession at that point likely, but dual possession goes to the offense by rule.
After landing on his head for the completion of the catch, he rolled over and it was stripped. TD done & dead before that to my understanding. I thought incomplete at first also, b/c only one foot landed before the roll over DB's body, but a head definitely counts as down.
Remove the defender and it's not stripped away after he controls the ball and is down in the endzone. There's no football move once down by contact.