I am the developer of the app Speech Central, one of the leading text-to-speech apps in terms of features, user satisfaction, growth and overall usage. Starting from August 1st 2021 the app is completely free for the blind people without any hidden cost.
There is no trick, my revenues from other users are enough to support the ongoing development of the app and I have decided to help to those in need. I believe that the app meets or exceeds the features of other leading text-to-speech apps on the respective platforms, and I'll be glad to hear suggestions for the new features and improvements.
Those are links to get the app (the Pro mode will be activated if it detects that you use some assistive technology like VoiceOver):
iOS:
$1Android:
$1P.S. at the moment the app exists for the macOS too, but as it is a paid app it is not possible to detect whether the user uses some assistive technology before the purchase and as such it is technically impossible to make it free for the blind users only.