[Aardwolf]

Yeah, with an electron beam it's clear that it's a continuous signal and a single beam is being controlled, but how do you drive millions of individual digital pixels all at once, how does the signal get routed correctly to each one if them?

[p_l]

with older HDMI/DVI displays, AFAIK you sync pixel clock to "address generator" for the matrix, with major issue becoming scaler AFAIK.

DVI (and thus older HDMI) being essentially "VGA that skipped Digital to Analog conversion" you're riding the beam, including porches.