After accounts on IBM Watson and Google AI expired, I am actively looking for a simpler substitution.
Arduino Project Hub:
https://create.arduino.cc/projecthub/msb4180/speech-recognition-with-arduino-and-bitvoicer-server-460477
BitVoicer:
http://www.bitsophia.com/en-US/BitVoicer/Overview.aspx
https://www.bitsophia.com/en-US/Store/Store.aspx