Hi Alan,
At our Zoom session meeting on 11/1/2020, Sunday, you asked about how many persons were using a trackball mouse. I didn't comment due to the amount of talking but I thought you might like to know that I use a Kensington Orbit Trackball Mouse with Scroll Ring (K72337US) on my HP Omen desktop computer.
I am very much impressed with it. My hand remains stationary and the cursor control, clicks and scrolling are all by fingertip motion. I can use it all day without my hand getting tired.
It goes for around $32.00 on Amazon.com. Who knows how much elsewhere?