Vosk speech-to-text means my initial voice prompts aren't sent out of my phone, and RHvoice means the TTS responses wouldn't be either, right? At least in princ

Vosk speech-to-text means my initial voice prompts aren't sent out of my phone, and RHvoice means the TTS responses wouldn't be either, right? At least in principle. I understand virtually anything you use a digital assistant for involves lots of internet. But it's tantalizing to imagine writing my own skill that would be heard and responded to by my phone with no internet involvement.