I'm pretty sure that this TDS 684B has the same kind of CRT. When I take a photo of the display, you can often clearly see it switching from one color field to the next in the middle of the screen.

As for the HP touch screen, I tore down a bunch of HP 16500A logic analyzers and reverse engineered the touch screen PCB. It uses a pretty simply LED/photo sensor matrix. You can see the PCB in one of the pictures here: https://tomverbeure.github.io/2022/06/17/HP16500a-teardown.h....