Are the current "childcare agencies" for arranging a childcare provider to come to the home and watch over the children? Can you elaborate a little more on the "childcare agencies"? How long are the engagements, how many days a week and how many hours per day, etc.?
Think about the benefits for employers. Campanies who allow WFH probably would appreciate it if their employees can focus on work and not the kids.
Don't think about how to scale this yet, concentrate on signing up just a few businesses. I'd start in a locale that has an intersection of the following: 1. Existing customers who'd be willing to champion this with their own employers. 2. A "childcare agency" that is reliable and you trust. Considering they are taking care of kids, hopefully this won't be too hard to find. 3. Large employers known for allowing WFH.