> "Compromised" meaning that malware hasn't been installed or that it's not being accessed by malicious third parties. This could be at the BIOS, firmware, OS, app or any other other level.

I don't believe there is a way to be 100% certain, but if I had to go to a store and pick a new device with the lowest likelihood of being compromised, it would be a desktop, a laptop, or a tablet running ChromeOS[1].

[1] https://www.chromium.org/chromium-os/chromiumos-design-docs/...