What I would like to know is; how much EMF/RF does an average scanner emit?
No more than your TV, electric lights, or phone charger. In fact, quite possibly less. Certainly far less than your cell phone, laptop, or Xbox controller, all of which contain intentional transmitters.
A scanner does not emit anything intentionally because it does not transmit. There are, of course, unintended emissions, but then this is true of any electrical device. It is especially true of modern, high speed digital electronics.
Most jurisdictions have some authority which limits the maximum permissible unintended emissions for devices. For example, in the USA this is the FCC. To sell a product, a manufacturer must submit a prototype to an electromagnetic compatibility (EMC) testing facility which measures the very small, unintended emissions of the product. The results are sent to the FCC which must certify the device before it can be sold.
So if you want to know more specifically how much EMF your scanner might emit, check out the regulations in your jurisdiction.