I can understand that sometimes facetime and similar can actually be quite distressing. At the beginning of lockdown, my adult children arranged a family zoom meeting, mainly for me. I burst into tears as I went into, seeing them all there, and - somehow, it only emphasised to me how different things were. I would never repeat it.
Do use zoom for lectures and meetings, but not for family. prefer to talk to them either on the phone or to receive letters.
Obviously, anything you do should be with the knowledge and permission of her parents.
Ask them if it would be okay to send letters by post and even small gifts - do remember to also include the younger child in these.
Children of 6yrs upwards are having a very difficult time - the whole world, which adults should be in charge of has collapsed - and many of them are very, very frightened and scared of anything happening to their parents.
So, take it slowly and carefully - and always with the full knowledge and permission of parents - and hopefully, things will get a little better soon.