Comment by advisedwang

Home Assistant [1] can be a voice assistant (both on phone and on dedicated devices). It's FOSS and can be fully local [2]. It's really gear towards home automation though, so its suitability depends on what you want to do with an assistant

[1] https://www.home-assistant.io/

[2] Although frankly to have a fast-enough and good-enough LLM you might need to use a service