How to make a display screen for a web cam/any digital camera?

Hi, i am an amateur, so sorry if this question has already been answered or is very basic!!

I am looking for a way to stream the camera feed on screen. My only criterion is to make it as simple as possible. Something which displays the camera feed on a monitor/screen/display of around 10" with a hit of a button. I am avoiding using an off the shelf android tabs or security cams as it involves a third party app, setting up the device, keeping device updated and all such steps. I want to avoid that. can someone please help?