Sensor if Dad Isn't Up and Around

I want to set up a sensor that senses if my Dad walks by. He’s sensitive about his privacy, but I’m afraid he’ll fall and no one will know for hours. (He’s 94.)

I’m thinking it would sense him walking by, but only alert me if he doesn’t walk by by a certain time.

What I’d like is to find a sensor that can stand alone and send a bluetooth signal to a raspberry pi. The rasberry pi would then use something like IFTTT. Thoughts about what sensors might be able to do this?

Alexa Spot and “Drop-In” function?

If you want to go DIY route, ultrasonic (HC-SR04) with ESP Thing. If you want easier quick connect stuff, maybe look into QWIIC (e.g. HC-SR04 and ESP32).