They do this on certain cameras, look up "Dual ISO". Effectively they make every other line more sensitive, increasing dynamic range when they merge the lines together. It's not a perfect solution, moire and other artifacts increase, and you lose resolution. The trade-offs are often worth it, especially for video.

Thanks, that search term did indeed show some interesting hits.

Fuji did this with “Super CCD” sensors in the early 2000s.

They used micro lenses, which had some overall sensitivity and angled aliasing challenges, but the results were impressive for the time.

https://en.m.wikipedia.org/wiki/Super_CCD

See this link, that's likely what this sensor is for: https://www.sony-semicon.co.jp/products_en/new_pro/may_2017/...

You’d be decreasing overall image resolution.

HDR is as simple as taking multiple exposures and different EV values. It was often down with sheet film cameras, the two negatives being used to create the final print.

Taking multiple exposures is not always simple to perform with good results. It requires a fairly static scene and camera.

And I doubt most people really need effective 48 MP mobile cameras. They could very well do with more dynamic range though.