I would love to get rid of my Echos and lock down my network, but I can't find a self-hosted & open source smart home voice solution that can match the Alexa ec

I would love to get rid of my Echos and lock down my network, but I can't find a self-hosted & open source smart home voice solution that can match the Alexa ecosystem. I do have my smart home on a separate network that's highly monitored, but I really wish I could completely lock it down so it couldn't talk to the outside world at all. I would be totally willing to pay for a self-hosted solution to Alexa just for smart home automation/control