You have the height and width switched. NES is 256×240. However, the top and bottom 8 lines are usually black, so games have a 256×224 rendering area, which is then included in a 256×240 image, which is then stretched to 320×240, making games look like 320×224. There's no way to force a WiiWare game to emulate this, AFAIK.
Human vision is logarithmic, it's not linear. And nits doesn't tell the whole story of perceived brightness. OLED'S look brighter then LCD's even when both are set to the same nit values because of the higher contrast ratio on OLED's
"And nits doesn't tell the whole story of perceived brightness" it's not about perceived brightness it's about all HDR content in TV and movies being mastered for 1000 nits so it doesn't look right with anything lower, it's also about dynamic range
OLED's can get away with a lower peak brightness and still provide punchy HDR because of their contrast ratio. Like I said human vision is logarithmic. The higher the peak brightness the diminishing returns in perceived brightness.
@The Real Jdbye Oleds hit around 750 nits nowadays. The difference between a 1000 nit and a 750 nit isn't huge. It's only about a 4% increase in perceived brightness. Not huge at all. You'll need at least 2000 nit displays to notice a bigger difference.