I noticed today that /e/ did experiment with Vosk ~1yr ago and packaged alphacep/vosk-android-demo with additional integration (choose language) as foundation.e.voice. You have to sign the apk yourself before install.
If you activate it as input method (slide to on as for aosp-keyboard) you can use it through the mic icon on any input field… though when I do, I’m blind to how to return to text input and am stuck 
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