But the OP's mother is showing no interest, love or caring about either.
I don't think that's true. She's not showing the interest, love or caring that the OP would like, in the way that she'd like. That's completely different. She has a vision of what a grandmother should be, and is finding her DM wanting.
I can't imagine not wanting to be involved with my children's children
To each their own. I can't imagine wanting to be terribly involved with my grandchildren, knowing who their friends are, what their school days are like, the minutiae of their ups and downs, their plays and piano recitals and football tournaments. I would want to know that they're well-adjusted, happy, enjoying their childhood, getting what they need from their parents, getting a good education. I'd love to have them over for lunch now and then, share any common interests if there are any. If they have any health issues, physical or mental, of course I would worry but there are professionals around to help with that (I'm not one) and I would encourage my child to consult them. I would want to know only as much as my child would want to tell me (which in reality would probably be a lot, knowing them).
Of course I'd want to see and spend time with my grandchildren, but they and my own children, once grown, would not be my day to day priority. Of course, if disaster ever struck, I'd drop everything and be there for them. But I can well imagine going for months with just texts or FaceTime or calls. Life is busy. Children and grandchildren should be busy doing whatever they do. They shouldn't be hanging around me!