With USB? That's impossible (thanks to the USB standards consortium).

The only reasonable method to do so would be to include another USB port, so that you would have one for charging, and one for USB use (keyboard, plugging in USB devices, etc..) but that would be confusing to people and increase manufacturing costs which would be passed onto you, the consumer.

Another method would be to simply not use the USB for charging, but that's not likely as Europe is pushing manufacturers toward this standard (most companies have agreed to it already anyway to reduce e-waste from incompatible chargers). And some governments are talking about putting a "e-waste" tax on companies that don't do something about the problem of electronics (basically it's either you recycle the old electronics or we'll tax you for the cash to pay others to do it).

Lastly, the 3rd method would be to ignore the USB standards consortium and implement USB host mode on a USB port capable of charging. But then you can't call or advertise that as USB or you get sued.

I believe HID bluetooth keyboards work partially, but some key functions are impossible.

No idea about bluetooth mouse, I would like to see it though. TV + Bluetooth keyboard + Bluetooth Mouse = temporary replacement desktop