A while ago I was struggling with not being able to see my kids and grandchildren, but I was determined to stay connected to my volunteer activities from a distance. As a result, I ended up taking a difficult and somewhat unpopular position to "do the right thing " in one group and prevailed. On one of my worst days personally, I received a handwritten
card from another volunteer thanking me for helping the group get to the right decision. I treasure it. So a simple card or letter is one possibility.
Another thing you might want to do is to write a memoir for your grandchildren about your past and their Dad's. It may not reach them for many years, but they will appreciate it. My cousins, now in their 60's were kept away from us for years, and we have spent many hours telling them about our grandparents.
Sue