I tried to fit smart appliances for my mum, there’s a routine on Alexa I think, which informs you if a smart plug isn’t used, or a door isn’t opened.
The intention was to get a notification of she didn’t use the kettle in the morning, or didn’t open the front door all day.
She has engaged with her neighbours now and isn’t sufficiently isolated to need it, but we investigated during COVID when she was very isolated indeed.
It shouldn’t be beyond the wit of man to develop a system that works to send alerts from homes where vulnerable people are at risk.
I can’t believe it would be expensive.