Thank you @trybick! This is great work. You're right that it's a large issue. (In the future, I'm also going to add issues for converting class components to function components, so I'll make sure to split those up when I do.

I see what you mean regarding initialState. Styleguidist didn't actually require defining initialState, so for those examples, you can add something like const [value, setValue] = React.useState() without passing some initial state.

I added a commit to your branch fixing the issues for the ButtonSelect, Card, and Checkbox components. Feel free to take a look and pick up from there. If you can't get to it, I can do the rest eventually.