Yeah this is the easiest way to get started. You probably want a low travel keyboard and ideally a low-latency-variance one to make it easier to find the start. It can be tricky to find where the update ends too because you usually see several frames of lcd switching.
The more advanced version is putting together a microcontroller which acts as a usb keyboard pressing a key, then backspace, then the key again, and uses a light sensor aimed at the right part of the screen to detect rendering in a repeatable way (slightly different fonts/ positions might change when it triggers but that’s likely on the order of a few ms tops, much less than the variance from frame boundaries).
The more advanced version is putting together a microcontroller which acts as a usb keyboard pressing a key, then backspace, then the key again, and uses a light sensor aimed at the right part of the screen to detect rendering in a repeatable way (slightly different fonts/ positions might change when it triggers but that’s likely on the order of a few ms tops, much less than the variance from frame boundaries).