Apple’s accessibility support
If you need help with accessibility features on your device, head over to Apple’s website. There’s a special support section, found at support.apple.com/accessibility, which has a number of useful tips and guides on using accessories like switches, as well as the various ways Apple’s products are designed to assist with different disabilities.
There are also resources for developers to help them build accessibility features into their apps. As well as that, Apple’s support section contains links to the accessibility aids it sells in its online shop. At the time of writing, Apple was selling a number of switches, trackers and mounting arms, plus skins to enlarge the letters on your keyboard so that they are easier to see.