Yay!!! I love scratch and make accessible games for my kids on it frequently. They recently added the ability to integrate a Microbit into the code which let’s you have an easy physical interface to your games. Similar to the Makey Makey but lower cost. You can integrate the accelerometer from the board to navigate the x,y plane in Scratch as well as the A/B buttons.
I also made a little project using the Gemma MO to make a finger tip glove game that triggers button presses when finger opposition happens. Here is a quick video.
Microbit Makecode also has block based programming and can connect to Bluetooth on your computer or tablet for additional functionality.
There is also a British company: Help KidzLearn that has many simple single and two switch games: https://www.helpkidzlearn.com/
I personally, would love to have a “hackathon” day where we get together and make Scratch games that are single our double button accessible. Let me know if this is something interesting you would like to collaborate on?