I really wish Trailhead would make content accessible. There is still no audio playback for the trails and that is how I learn most effectively as a special needs individual. It also took me forever to get to this page from the Trailhead mobile app when I click leave feedback. It should go right to the field since I am already signed in on Trailhead.
For Trailhead in particular, I have found that Microsoft Edge's native text-to-speech reader works pretty well. It is able to properly navigate the layout of Trailhead, unlike some text-to-speech programs. You can also select a voice and speed that works for you. Chrome has a native one that I have found to be particularly problematic. It cannot navigate the page properly and gets stuck on the navigation pane.