Most “Smart” TVs use Automatic Content Recognition (ACR), essentially taking snapshots every 10+ms of what you watch and hear, then forwarding & selling that data to companies for ads, etc. I now feel it’s only a matter of time before this “feature” finds its way to our ever “smarter” PC monitors.
LG with the help of Windows is already installing adware when the right Device ID is detected.
☑️ To disable ACR on TV: https://www.zdnet.com/home-and-office/home-entertainment/how-to-disable-acr-tv/
Actually, unlike on Windows, fwupd itself contains the code to flash firmware on various types of devices, and all the manufacturer provides is the firmware file itself.
On Windows you can (apparently) provide an arbitrary installer yourself instead. That said, theoretically a UEFI upgrade could mess with your system since that firmware ends up running on the main CPU itself.
It is also conceivable that you could have rogue firmware on some other device that can mess with the system via DMA (direct memory access). But then we are talking full on hacking, and likely unreliable across different kernel versions etc. Notably monitors don’t have such access. Enabling the IOMMU should also help protect against this (since that restricts what RAM addresses each peripheral can access).