I've been thinking about that myself. Sweden was famously, among low carb/high fat circles, the first country to stop officially demonizing saturated fat. To those of us who follow this sort of metabolic chemistry research, it means that Swedes are less metabolically damaged. The metabolically damaged (overweight, obese, diabetic, heart disease – it's all on the same spectrum) are those who suffer more severe cases of Covid.

There is that big spike of excess Swedish deaths at the beginning of the pandemic. However, the previous year Sweden had a lower than average overall all-cause mortality, so 2020 was doing some catch-up; and I think in any country, the virus picked up the elderly and the sick who would have died soon in any case. So maybe that initial spike is not as significant as it might seem at first.