Isolation is very difficult indeed but these risks are what parents and children have had to deal with through all of human history up until our last couple of generations. We've become extremely spoiled and have been chasing self actualization in Maslow's Hierachy in this society for all our lives.
Well now that shit is gone. We dropped way to the bottom with this pandemic and now are scrambling to satisfy physiological and safety needs. I'm sure parents and kids during the London Blitzkrieg wanted to go out and play and go to school and pretend everything was safe too. Same for every location in every society that deals with widespread disaster, war, famine, and disease outbreaks. But it's not a luxury to be afforded when mere survival is the front most pressing need and we are smack in it right now in the USA.
Your kids' isolation issues can be managed and overcome. Their permanent brain/lung/heart damage and/or living with the guilt that their school activities led directly to mom/dad/grandma/grandpa's deaths cannot.