I want to second what a fine feature this would be. I switched from Google Keep to Evernote because of the intuitive way it displays lists and notebooks. But Keep has got the checkbox feature right:
a toolbar item for adding checkboxes
A menu item called "Delete checked items" that operates on notes
That's all you need. You certainly don't need special machinery inside checkboxes. Then you could have lists called:
Books I need to get
etc, and they would all work properly. Since Evernote lacks "delete checked items", I still use Keep for these functions. I'd rather I didn't have to.