Well we have egg/s! I watched her yesterday and all morning she was poking her head out of the entrance hole and he was feeding her. Afternoon, didn’t see her again. It was the same the day before so I thought I bet she is laying eggs in there already! So early evening I went out and looked, nest is pretty shallow like you said about your nuthatches Gin. I thought I could see an egg slightly through the nesting material, felt it lightly and yep there as an egg. There might have been two, not sure. Everything was covered like a chickadee almost except no blanket, like she hid it in the nesting material. Will check again in a few days, sounds like they have a pretty decent sized clutch normally.
Donna in WI