But, you can turn off the Sidebar filters in the View menu, such that they now appear at the top, where you can select “Number of Children contains” and enter 0. However, since it’s a text search, it will also return families with 10 (or 20, or 30, …) children.
In case others are wondering, the Number of Children column is a part of the People/Group People views and not the Families view. Which I again find curious.
I forgot that those "Number… " columns were there. I have never used them. I just use the Relative gramplet in the bottom bar for other family members.
But I renew my major complaint with this method. The first person that returns as valid for this method was my mother’s sister who lived 1 day. While she in fact never had children, I do not know how that could be of any use.
I leave it to @n88yanks to determine what meets his needs.
Actually, I hacked my copy of the Families view to include Number of Children and forgot that it was my own customization. I started adding columns to several views, and then decided it would be better to create new views as addons that could be shared, but I haven’t progressed much further on that yet.