I'm so very, very sorry for the loss of your great grandson. A new sewing lounge opened up in our town this past year & one thing they do is make angel gowns. They have set aside the third Thursday of each month for volunteers to come in and help make the gowns.
Here are some sites that I found that might help you:
https://diydanielle.com/angel-gowns-...ress-tutorial/
https://dying.lovetoknow.com/Baby_Be..._Gown_Patterns
http://www.easyfreepatterns.com/pree...-patterns.html
https://www.ravelry.com/patterns/lib...iny-angel-gown