For my wallbmount tablet project, I am looking for tablet charger module with usb C type output which I could directly connect to the wires in my wall socket, and hide it into drywall. But I am not sure what I should be looking for. All I get is some calsic chargers, or DC 12V/24v to DC 5V converter.
No this is never ok. You can never bury an electrical connection is needs to be accessible.
You get a recessed outlet behind the device. For neatness would get one with a usbc onboard but either way works. These are typical for behind tv’s and the like.