Look into some of the products and services used in Japan for elderly care at home.

My FIL, in his late 80's was living at home alone. My wife used a monitoring service, provided by local package delivery company. They installed motion sensors in the toilet and on the door. If no motion detected for 24 hours, the company will alert my wife by phone and send the nearest delivery driver to check on him.

I myself have tried Home Assistant setup on Raspberry Pi and variety of sensors for different purposes.