Most people in North America are deficient, getting sun is also problematic because of skin cancer. If there was a single nutrient that people should supplement - Vitamin D is probably the one. Sunny days aren’t enough, much of the year the atmosphere is too thick. One doctor suggests D supplements year round - not just the winter months, to ensure an adequate level.
I think the skin cancer risk is overblow, but that’s just my opinion, FWIW.
That said, in some locales, it’s just not physically possible to get adequate sunlight producing UV.