Distance changes the shape of a grandparent relationship, but doesn't have to diminish its closeness with intentional effort.
Build a routine, not just occasional visits
A standing weekly video call, even short, builds more familiarity over time than infrequent but longer visits alone.
Create shared, ongoing activities
A shared book you're both reading, a recurring simple project, or mailed letters and small packages give the relationship structure between visits.
Ask the parents directly what kind of contact works well for their household's routine and the child's age — this avoids well-intentioned overreach.