Re: Tutorials for sighted users.
Not that I'm aware of. But I can give some useful input.
Make certain that they have the latest version of NVDA and that they have gone into NVDA settings, Vision, and turned Focus Highlight, with all its options, on. This is the easiest way for a sighted person not only to know what has focus, but what state NVDA is in on the object with focus. If they need to, they should print out a brief cheat sheet as to what the outline colors and styles tell them about NVDA state at that moment.
I'm not quite sure which aspect of keyboard navigation you're trying to get someone to "get the hang of," but if it's quick navigation in web browsing the easiest way I've found to do that is to make the tester aware that the capability exists and give them the section from the documentation with those single key commands, and, if possible, walk them through using the most common ones on a web page or two that's fairly typical. Things like Google Search results, using the H shortcut to move from returned item to returned item, rather than L (which will involve other links not of interest), is a good way to give a brief introduction and to show how those two differ from one another in practice.
Speaking strictly from my own experience in learning screen readers, period, the only way is to play with them and, if possible, with a bit of initial guidance (which I really didn't have) from someone who actually uses one to get across the basics of what one does day to day, and how. It need not be a long intro, but brute force TABbing around tends to be the navigation of choice only because it's most easily stumbled upon (and it's grossly inefficient). The web browsing single key navigation shortcuts are very easy to pick up on and use if you are made aware they are there, and someone shows you, when you need to do a "massive jump" from wherever you might be to a button, or checkbox, or whatever, that this can be achieved with much greater ease using those shortcuts than many, many hits of TAB.
Brian - Windows 10 Pro, 64-Bit, Version 1909, Build 18363
Science has become just another voice in the room; it has lost its platform. Now, you simply declare your own truth.
~ Dr. Paul A. Offit, in New York Times article, How Anti-Vaccine Sentiment Took Hold in the United States, September 23, 2019