So, in case of doubt, call on your friendly IFAB... It appears to me the the relevant section of Law 12 is as follows:
"If the goalkeeper handles the ball inside their penalty area when not permitted to do so, an indirect free kick is awarded but there is no disciplinary sanction.
However, if the offence is playing the ball a second time (with or without the hand/arm) after a restart before it touches another player, the goalkeeper must be sanctioned if the offence stops a promising attack or denies an opponent or the opposing team a goal or an obvious goal-scoring opportunity."
Even if it was just a rebound, the ball touched the attacker before again contacting the GK, so no foul, no sanction, no how.
As I understand the situation and as I understand the Law, even signaling advantage (if you did so formally as opposed to letting the play develop) would be unnecessary.
Am I wrong about this?