The elephant in the room is that big confounding factors can be expected: healthy people get more sunlight; also, people who go outside more during the daytime

The elephant in the room is that big confounding factors can be expected: healthy people get more sunlight; also, people who go outside more during the daytime are likely to have healthier social lives, which is big for CVD. So the question is, how much, if any, does the sunlight itself benefit health, given that we could expect a strong correlation even if the answer is "negatively"?