I’m sorry to hear this. Death of such a great man who meant so much to you will be hard. Sounds like a great role model for his grandchildren and their children. A big loss. Jesus already greeted him with a welcome Home hug. As is written, absent from the body, present with The Lord.
2 Cor 5:6-8
"Therefore we are always confident, knowing that, whilst we are at home in the body, we are absent from the Lord: (For we walk by faith, not by sight)"
"We are confident, I say, and willing rather to be absent from the body, and to be present with the Lord."