Hi all,
Barrie from One Switch dot org has a great list of resources for people interested in developing single button games for accessibility.
Scroll down to 'Writing a Switch Game' for the scoop. https://www.oneswitch.org.uk/art.php?id=9
It took me ages to refind this resource despite remembering almost exactly the right name and the authors name because the Nintendo Switch has made finding resources difficult but it should be helpful for people who have never considered how to make an entire interface single button compatible before.