Discover / find hidden illegal spy hardware?

Hello all

I know, that hardware can function without it being shown in Windows Device Manager.

1.
Is it possible, that someone could install hidden cellular hardware in my laptop, and then use this hidden hardware to steal my data – if yes
Could this traffic be hidden from Windows Resource Monitor Network?
Are there other ways I could discover this hidden traffic?

2.
Is there somekind of handheld scanner, app to phone, which could scan around the laptop and see if the laptop emits wifi or cellular signal?

Thank you