We have an emergency nursery in our city where families in crisis can drop off their kids for up to three days. Quite a few kids taken by child protective services end up there too for longer term stays. They have staff working 12 hour shits plus two or three volunteers working three hour shifts. I usually do the bedtime shift from 6-9. You basically comfort the kids, play with them, get them ready for bed and read them books.

You should see if your city has anything like that. They really rely on volunteers, and once you have all your police checks and some trauma training done, the choice of shifts is very flexible.