I use a Mac now, but have a Windows VM running in Parallels. Paint.net is one of the first apps I installed on that VM. It's ridiculously easy and intuitive.
The closest program I've found for Mac is Pixelmator Pro, but it's not free, and the UI/workflow is more complex in my opinion. Paint.NET is still one of my favorite pieces of software on Windows.
I spent SO. MUCH. TIME. in computer stores (yes, they were a thing) as a kid in the 80's, and the Compucolor was a favorite. The keys with different colors! Everything was opinionated and geeky. And hardly any demos existed, so the computers were wide open to experiment with.
Yeah, but lots of parents lie far more often than would be useful for a child. But more importantly, absolutely honest is not the same as absolutely open. You can be absolutely truthful in the things you say without causing harm. If you think the truth would cause a child harm, then direct them away from a topic or tell them they aren't ready, etc.