I have never heard of this either!
We had one when our little one started nursery. It was just to come meet my little boy at his place of comfort. It's something they do to help kids settle at nursery. They were as t our home for 20 min. Just sitting, observing my little one and trying to interact with him.
I had a home visit before my daughter started nursery. It was just so they could get a better understanding of my daughter. They wanted to see her in her home environment so they knew if she was settling ok at nursery. They asked me some questions about her needs as well. I thought it was a very worthwhile visit
I’ve never heard of a nursery doing a home visit. Have they said why they want to do it? Or is it standard practice for them to visit everyone’s home?