For OLED panels (or LCD panels with backlight modulation) it'd probably be better to chart grey contrast rather than black contrast - the ratio between the maximum and minimum possible nonzero illumination level. Black contrast with a panel that can turn off a pixel/zone for 0-level will always end up with a divide-by-zero issue and a completely worthless chart. Grey contract (full brightness over minimum displayable brightness) actually gives you a useful measure of real world contrast.
e.g. a screen that can produce 0 nits at 0 input level, 1 nit at an input level of 1, and 1000 nits at an input level of 255, will have much higher perceptual contrast than a screen that will also produce 0 nits at 0 input level, but produces 50 nits at an input level of 1 and 1500 nits at an input level of 255.
The naïve max-brightness-over-zero-level charts are about as helpful as the old 'dynamic contrast' measures manufacturers liked to slap on monitors with backlight modulation (where a TN panel could magically produce a 80,000:1 contrast ratio).