If its safety related, use a paid for tool if you can afford it. The cost you pay for is for all the testing and reliability, that you can’t replicate with a diy solution.

You’ll feel terrible if something happens and your solution doesn’t work in the moment.

You could try Rhasspy - https://github.com/rhasspy/rhasspy

Mike is a pretty cool guy. I know the repo is archived, but he might help you if you reach him.

Alternatively, what about a panic button? Both commercial solutions and privacy friendly local solutions exist. I know it’s intrusive and grandma will have to keep it on her person at all times. But… that’s kind of what they’re there for.

Thanks for the suggestions everyone. In broad strokes, here’s the thinking to reply to a few comments at once:

1. We didn’t want to use a phone-based solution because she doesn’t always carry her phone in the middle of the night. This goes for carrying a button.

2. A LifeAlert system could work, but they usually involve buttons.

After talking about it, we realised that simply putting out a baby monitor or equivalent might be the most effective - she can shout at it and it will go direct. An alternative would be setting up a HA alert to broadcast based on a phrase (or a few). We’ll weigh up the options but I’m leaning towards the former.

Thanks everyone! I appreciate the ideas - I think HA might not be the solution after all, but hopefully I can keep them from installing wiretaps Amazon Alexa in their house.