You should let play go and use the resources you have available, linesman, VAR etc.
None of these are relevant in the case where Grealish doesnt get the ball first (which he mistakenly thought was the case). VAR can’t go back and give City a free kick.
Nope, there is nothing in that incident that would allow VAR to intervene. They can’t overturn a free kick (or lack thereof) or advantage. VAR is literally irrelevant to this specific case, no matter what decision Hooper makes