Earlier quoted context omitted.
I had a similar issue - the glass on the back of my Pixel (5 I think?) cracked right by the power button, and it seemed to be kind of OK but I got a new phone anyway, but left the old one in my glove box of my car where I used it for the bluetooth entry to the parking garage at work (and because re-enrolling was a pain). It didn't have the sim setup or wifi enabled so didn't think much of it. This worked fine for a f…
In Germany it is not possible to call emergency without an active SIM (if it is PIN protected, the PIN has to be entered before). This has been deliberately disabled since February 2009 because there were too many anonymous calls for fun or (how idiotic!) to test if a secondhand phone still works.
The solution you describe sounds like a potentially dangerous technical solution to a cultural problem. I don't hear of people phoning 999 in the UK to test a second hand phone works, or for fun.
What happens in the case where the only phone to hand happens to be someone else's and said person is incapacitated, or otherwise incapable of unlocking it?