I am wondering if there is a chat program that works locally when the internet is out but still be connected to from the internet. I know this will be something that is self hosted.
Bonus points if I can set it up on the raspberry pi that is running Home Assistant.
Aah, yes. You’re right there. You will require a domain for it to work. Although, you could still have it work with a local DNS server for internet outages. You would still be able to chat locally in that case. But yeah, this does not seem like what OP is looking for.