People with motor disabilities use a wide range of adaptations, including keyboard-only navigation, switch devices, voice control software, eye-tracking systems, and modified pointing devices like head wands or mouth sticks, depending on their specific needs. The common thread across nearly all of these is that they route through the same core accessibility requirements: full keyboard operability, generous target sizes for buttons and links, and enough time to complete tasks without abrupt timeouts.
This is why keyboard accessibility, often tested simply by unplugging the mouse, is considered one of the highest-leverage things a team can get right, since it benefits screen reader users, switch users, and voice control users all at once.