There are various home assistant solutions out there but all of them transfer your voice to some server for processing. This is a no-go for sane people although the technology is interesting and could be useful. There are various open source tools out there to achieve the same result but there is no turn key open source self hosted solution. The goal of this project is to implement a way to have a home assistant running locally - ideally with one command.
The project that is closer to the desired result is Mycroft (https://mycroft.ai/). It is very easy to run the client side components using one docker command but their backend is running remotely. All the tools they use though are open source so it only needs one to do the work and package them in a nice little docker-compose file (https://mycroft-ai.gitbook.io/docs/about-mycroft-ai/faq#can-mycroft-run-completely-offline-can-i-self-host-everything).