Switch on “Alternative Pointer Actions” in “Accessibility”. That by default gives you F11 for a left mouse click and F12 for a right mouse click. You can also

Switch on “Alternative Pointer Actions” in “Accessibility”. That by default gives you F11 for a left mouse click and F12 for a right mouse click. You can also configure things so that you can use facial expressions to do this. That way, you won’t need a keyboard at all. (“Mouse Keys” also allows you to do a right click from the keyboard, but likely goes to far for you, taking over part of the keyboard for moving the mouse)