Usb device as simple event sensor on/off

Hardware
1

Hi.
Im frequently running into issues when trying to use automations based on anothers device turn on/off event.
Specifically right now, a smart tv.
But no options avail to have a reliable on/off event/trigger.

I wonder if such usb (or other) device exists, which does simply nothing more then sending a power on/off state whenever its under power.

Usb device could be plugged in to tv, whenever tv has power or not, the usb device reliably has a on/off state to be used for any automation.

Is there such thirdparty usb stick (or similar) sensor available out there?

2

You could use esp devboard powered from usb and flashed with esphome.

3

power plug
An alternative is to use a smart plug attached to the smart TV so when It’s on you know the device is on and you also have the ability to automate the TV turning on. If you needed to have the TV in standby you could use a smart plug with power monitoring and then base your automation on the power use of the smart plug.