It would be useful to be able to scale the text of a note in the mobile version. Currently it is possible to zoom in and out but a feature where you can scale the size of the text so that you only have to scroll up and down and not horizontally would make easier to read the note.
Some apps have a "Print View" that is very similar to the current zoom in/out function. But they also have a "Mobile or Web View" that allows scaling the text.
I'm on iOS, and my mobile version reacts to Apple's dynamic type feature (i.e. app-by-app scaling). In the past, this wasn't the case, so that's a big improvement.
Can't say anything about Android, but there must be similar system-wide scaling mechanisms. And you're absolutely right: Customization options can greatly enhance an app's usefulness, especially when it comes to accessibility.