[porterde]

The visual feedback sounds very much like the strobe feature on my guitar tuner. I think the first like this was the Stroboconn in the 1930s.

[dsego]

Peterson is the most known for their strobe tuners I believe. There are nowadays many other desktop and smartphone apps and pedals that have a strobe mode, but some are real strobes and some are only simulated. As far as I can tell, a real strobe will recreate the effect based on comparing the input signal frequency to a generated reference. A fake one will just use the estimated frequency (done by a pitch detection algorithm usually based on FFT) but instead of a needle offset or LED meter it will show a steady moving pattern, but it's not as responsive or as reliable as the real thing.

[v15w]

The visual feedback uses time period (of ref note) and number of cycles to set the scale of waveform display. It doesn't depend on detected pitch.

I think strobe tuner's used neat analog electronics based reference and filters to visualise.

[v15w]

This visual feedback is very similar. It also shows octave changes i.e if the pitch detected is 0.5x, 1x or 2x the reference freq / note set.