I completely understand that a lot of people are separated from their grandchildren, and that it's not easy for anyone living through this awful crisis.
Nevertheless, if someone reaches out to say that she is feeling sad, it is not remotely helpful to point out to her that others have it worse, or that in some sort of hierarchy of pain, she is not at the top of it.
I was brought up like that - I was always being told about the poor children somewhere, or that my twisted ankle (or whatever) was as nothing compared to a broken leg, and at least I could walk, unlike the poor children who had had polio.
It took me until later adulthood to learn to own my own feelings, and to allow myself to just accept that I was sad, or felt ill, or was hurting, and that that was ok. I had a right to feel as I felt, however much someone else might be feeling worse on some subjective scale of pain.
I tried very hard to let my own children tell me about what they felt, and resist the temptation to belittle those feelings, and I hope I avoided repeating the past at least most of the time. There is no point, anyway - people feel what they feel, and adding resentment at having those feelings diminished will only make them feel worse.
I really don't mean for this to come out as some sort of lecture, and I apologise if it sounds that way (I think it might). It's just something that triggers all those feelings I had as a child that I was wrong to be anything but happy (or at worst, stoical) and that my real feelings had to be suppressed in case they annoyed other people.