I do feel for you as I'm in the same situation. I've been Grandma to four step-grandchildren since they were born (ages range from 18 to 14) and initially Mr. G and I were very involved with babysitting and then looking after them when they came home from school. Now 2 live more than 70 miles away and the other 2, just 18 miles away, we only see when we're invited - generally no more than 4 times a year.
"Other Granny" has been a problem in both families and one of them did say to me what has been said to you; "It's not as if you're their real grandma". The other is a very demanding, influential person (who I actually get on with) and she is absolutely obsessed with 18-year-old grandson, whilst 16-year-old granddaughter is fixated on dead grandmother she never knew!
My DH doesn't hear from his son or daughter unless he phones them and it's usually a rushed conversation because they are "so busy". We haven't seen one family since January 2023, and although we spent Easter Sunday with the others, we haven't heard from them since. It's painful for him although I have now trained myself not to think about it too much. It hurts me to see my lovely husband so ignored by his family. We have tried inviting them to brunch, to lunch, to dinner, but if they do come there is little socialising in that they talk to each other and not us, usually about people we don't know.
So sorry, this has now been all about me and not about how horrible it is for you, Layney. (Coincidentally once a nickname of mine ....). Just be assured that others feel your pain.
PM me if you think it would help.