Searching for: Offline Voice Assistant + Speech-To-Text + Privacy

Edit:
Seems that i did miss one very important topic, related to Sepia which is very helpful for me:

SEPIA Open Assistant - Privacy respecting, self-hosted voice-control - Apps & Services / 3rd Party - openHAB Community

Talk to your Smart Home via SEPIA Open Assistant | by Florian Quirin | SEPIA Framework | Medium

Im very impressed and i think this looks very promising to me