Hey. Have you considered to implement also functions for visually impaired people? With this simplistic concept of phone, it could be the target audience. Text-to-speech on all menus and displayed text message would be just fine.
thank you for this question.
How exactly do you think it could work?
We have many hardware limitations for the on-device Speech-To-Text, the other way (TTS) is simpler, but still requires a lot of work - it’s currently unsupported.
I think there is no need for “speech to text” if you have 0-9 letter keys (touch displays are a different story). I am not visually impaired and yet most of the time, when I type some text, I use only my haptic memory and I do not look at the keys. Text to speech would be fine but it is resource heavy for the Cortex-M7 you are using, if there are more important services running. And to be really multi-language, you would have to support at least some popular languages. This is indeed optional feature. As a minimal workaround I could imagine, that you have some static sounds for every menu item, that the user is able to navigate in the system. Also when typing the message, you can play the spelling sounds of the letters (just English ANSI characters). That way it should be possible to compose messages, basically for all languages based on latin alphabet, as most of them have ways how to transcode missing letters into combination of ANSI chars, eg. in german: oe = ö