For a radio to show its frequency on a numerical display, it must know its frequency. This complicates the AM superheterodyne receiver design somewhat from the most basic types that use a varicap or potentiometer to drive the VFO (Variable frequency Oscillator) of the superhet front end.
There are two ways we can know the frequency the radio is tuned to as a digital number. Either we control it digitally, or we measure it with some sort of ADC. We could for example use the standard potentiometer controlled VFO and measure the voltage of the potentiometer with an ADC to determine tuned frequency. When we calibrate the radio's passives we also calibrate this ADC to understand frequencies properly from pot voltages.
The more interesting way in my opinion is setting the frequency digitally. This requires building a digitally controlled VFO, and that seems interesting.