“...just as a Protestant asks their deceased grandparent/parent to watch over them.”
Never have I done this. Seems like sacrilege, to me. Christ and His angels watch over me very well, thank you very much.
....And the saints who are home with God as well.
You don’t ask or wish others living on earth to pray for you? Do you pray for others?
If you believe the saints are alive in heaven, why not ask them to add to these prayers?