
The Accessibility API makes it easy to know when a user has a screen reader enabled, as well as programmatically speaking labels through the connected screen reader.
import { Plugins } from '@capacitor/core';
const { Accessibility, Modals } = Plugins;
Accessibility.addListener('accessibilityScreenReaderStateChange', (state) => {
  console.log(state.value);
});
async isVoiceOverEnabled() {
  var vo = await Accessibility.isScreenReaderEnabled();
  alert('Voice over enabled? ' + vo.value);
}
async speak() {
  var value = await Modals.prompt({
    title: "Value to speak",
    message: "Enter the value to speak"
  });
  Accessibility.speak({value: value.value});
}