How to control the computer shutdown via USB when 220 power is lost at the input of the computer's 12V power supply?

Question

USB

There is a nettop with an external power supply, like a laptop. This computer needs to run 365 days a year, so the plan is to throw away its power supply and buy a 12V power supply with a battery. It is necessary that when the voltage of 220V is lost from the city for more than one minute (for example), a control signal is sent to the computer, upon receipt of which a certain sequence of actions is performed on the computer, for example, turning off the computer. Such a scheme is implemented on the APC UPS. And how to do without APC?

Answer 1

There are uninterruptibles for all kinds of boiler houses for private houses, etc. There, you need voltage at the output and they know how to give a signal to turn off the boiler.
Like
www.a-electronica.ru/catalog.html
If I did it manually, I would do it on something like Arduino.
You can connect a relay to it, which will determine whether there is voltage or not. There are also ready relays for Arduino.
And it would still be more convenient to notify the computer not via USB, but via TCP / IP, although it is also possible via USB.

Answer 2

I doubt the APC is much cheaper than a 12V power supply with battery.
Is it justified to refuse a ready-made solution based on APC?
APC has 12V batteries. You can try signing up with them.