Our parish (my former one, anyway) did this.
They allowed the Homeschool Coop to operate in the building one day a week.
I recommend this happen in a large parish, where the classes are away from the daily operations of the parish.
It was LOUD. Crazy. Really nice people, sweet kids, but they would come in my office constantly looking for glue, scissors, stapler, pencils, print something out for me please, …it was a zoo.
We loved them, but we could almost not function as an office when they were there.
It was totally up to our pastor. He would say a Mass for them to start their day, hear confessions once a month, and in general let them do whatever they wanted.
Super nice people. It was just ALOT to have going on.
If your parish has lots of room, it was a nice thing to do for them, as the nearby Catholic school was not to their liking. They were most appreciative.