Yeah, theres a couple cameras I know of that go up to like 42 megapixels or something, but I think thats so you can crop in digitally without losing quality.
One of the best low light cameras right now is the Sony A7SII, and I believe part of its good low light sensitivty is because its a full 35mm sensor but only 12 megapixels, so you get bigger pixels that can get more light.