Exactly two years ago my daughter, who then lived 300 miles from me and who I could visit by train, told me that they were moving to Massachusetts. My grandsons were 10 and 12 at that time. Like you, slwolfson, I was bereft. My husband is 85 and has dementia, and I knew that it was going to be hard work travelling to visit them.
Since then Covid intervened and not only is it unlikely that I will ever now be able to visit them, but they have not made any visits home, as they had planned, as my son in law is shielding. I detest facetiming and skyping, and felt that I would be jumping through huge hoops to stay in touch.
It's not been like that at all. Since they saw how uncomfortable I felt facetiming, all our calls have been by telephone, free, courtesy of Whatsapp, and usually longer than half an hour. I talk with and Whatsapp the boys independently of their parents - their main interests are sport and reading, and we discuss football (sorry, soccer!), lacrosse and books.
I am actually in touch with my daughter more than I was when she lived in England. We Whatsapp several times every day, discuss everything, share photographs. We talk roughly every 10 days.
I have found that she has needed plenty of support in her new life. Although she is a confident and efficient person, Covid, an 18 month search for a house, her father's dementia, have been uppermost alongside guiding her boys into the education system and supporting them when they had not been able to make friends or go to school because of Covid.
You will probably still grieve for the old, cosy life you had with the family, but their new interests and the fact that you do not need to travel abroad to see them, will compensate. It is really interesting seeing them navigating a new life and new State, and gives you lots to talk about. I take cuttings from local papers about things which interest my daughter, and we discuss books, tv, life in general. If you can encourage them in their new life and take an interest in everything, you will find a different kind of closeness. If you read to your grandchildren now, perhaps you could Zoom once a week and read them a story?
I wish you well in this new phase of your life, slwolfson. My life is not as I had envisaged, but there is still much to be content about.