In elder care, I am building https://statphone.com - one emergency number that rings multiple family members simultaneously and breaks through DND. Would love to chat/collaborate.
The question of "intrusion" was always interesting to me because old folks often face going from nothing to assisted living or nursing home which is often quite intrusive, where somewhat ironically adding a bunch of sensors to your home allows you a bit more privacy.
Kind of a tangent, but I like your type of system as an alternative to the emergency pendants. It always struck me as strange to expect old folks at risk of fall to remember to charge and wear a pendant at all times.
Good luck and for what it's worth, go for it!
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.