• ~3GB of disk space during installation; afterwards only ~2GB
• Termux
• Termux:API

• Install the following (open source) apps: Termux, Termux:API
• Open Termux and run pkg i -y git && git clone https://github.com/T-vK/Termux-DeepSpeech.git && cd ./Termux-DeepSpeech && ./speech2text

This will take a while beacuse it needs to download a pre-trained DeepSpeech model and a DeepSpeech release. It will probably also ask for microphone permissions (which are required for obvious reasons).

If the installation was successful, you should now be able to use command speech2text. speech2text will listen to your microphone for (by default) 2 seconds and then print the words that were recognized.

You could create bash scripts like this:

#!/data/data/com.termux/files/usr/bin/bash

WORDS="$(speech2text)"                            # This will listen to the microphone for (by default) 2 seoncds and the write what you said in the variable WORDS

echo "Recognized: $WORDS"                         # Show what you just said

if [[ "$WORDS" =~ "light" ]]; then                # If what you said contained the word "light"
    if [[ $WORDS =~ "on" ]]; then                 # If what you said contained the word "on"
        termux-tts-speak "Turning flashlight on"  # Let a robot voice say "Turning flashlight on"
        termux-torch on                           # Turn the flashlight on
    elif [[ $WORDS =~ "of" ]]; then               # If what you said contained the word "of"
        termux-tts-speak "Turning flashlight off" # Let a robot voice say "Turning flashlight off"
        termux-torch off                          # Turn the flashlight off
    fi
elif [[ "$WORDS" =~ "heating" ]] || [[ "$WORDS" =~ "temperature" ]]; then   # If what you said contained the word "heating" or "temerature"
    # Do whatever here...
    echo "Hello"
else
    termux-tts-speak "You said: $WORDS"           # Let a robot voice repeat what it thought you said...
fi

If you install the Termux:Widget app and save the above script under "$HOME/.shortcuts/tasks/" and make it executable for example like this: chmod +x "$HOME/.shortcuts/tasks/speech-command" (speech-command is the name of the script). You can then then create a widget that triggers the script. Or using the app HomeBot (open source) you can remap long-pressing the home button which usually triggers the Google voice assistent to run your speech-command script.

This is a very new script that has barely been tested. You might also have to install a TTS Engine (Flite TTS Engine is a good open source one) because I'm using text-to-speech commands a few times in the Advanced usage example.