I am Grandmom and my husband is Poppy, he was supposed to be Grandpop but our oldest grandson started the Poppy and it stuck. One grandson called me Memo (Me-mow) until he was about 7, I kind of miss that.
My parents are now Bip Pop and Grandmom, although she was Big Grandmom for a period of time and she hated it.
My grandparents were Gram, I shortened Grandmom to that when I was a teen and Grandpop for my dad's parents and Mama and Daddy for my maternal grandparents. I think it was more because we lived with my mom's parents until I was about 2 and that's what. everyone called them so that was what I called them. My mom's dad died when I was 6 and my grandmother remarried less than a year later for business reasons. She wanted us to call her new husband Granddad or a variation of it but my mom was adamant that we would NOT call him that. He wound up being Uncle 1st Name.
Congrats on your grandchild, they are the best