If you want to go the nursery school model you can still do that from your home. I know a lady that offered half day care with the option of 2, 3 or 5 mornings, 3 or 5 afternoons. She offered an early start and a later than school day pickup. She served a large snack but no lunch. She was actually full but it was also back when junior kindergarten wasn't available in all schools so that age group was her focus.
Another lady that did this was in an area that had full day but alternate day JK/SK to eliminate the need for noon hour school buses. She was able to sign up enough kids to have them on the alternate days so had two groups of kids that came with the understanding there would be no care on PD or school holidays and parents should make arrangements for camps etc.
You might be able to tap into the homeschool market with the idea of offering a group social program with lots of music, art, games but they would not be looking to pay a lot for the service since they do create their own programs amongst themselves.
You might find a church is interested in letting you run a program out of their facility or find a church that has a program that is looking for someone else to help.