Sweden's strategy was never to aim for achieving herd immunity though - I don't know where that particular piece of disinformation comes from, but it has been pushed by merican reichwingers and idiot fools like Bill Maher, people who just don't want social distancing and shutdowns, so I guess it's an easy canard to point at in their propaganda war of how things should have been done in the U.S. as well.
The actual strategy was simply to suppress the peak rate of spread of the disease below hospitals' capacity to treat victims, because if you run out of intensive care beds the deadliness of this disease goes up several hundred percent. Not shutting down daycare facilities or schools was to make sure hospital staff and other essential workers did not get tied up at home watching over their small children, or having elderly grandparents pressed into service as babysitters.
Where they really effed up was keeping the disease out of elderly care homes though, which led to a relatively high death rate, but numbers can also be somewhat deceptive. Not all countries test for the disease or report statistics in the same way. It's probably going to take a lot of time before statisticians can sort everything through and figure out comparable numbers for each country, if that can even be achieved at all at this stage. Like, it seems some countries did not test elderly people who died at nursing homes for the disease, only elderly who died at hospitals. Or only tested those who died at a hospital during intensive care, but not if they died elsewhere in the hospital.
If you don't have the test data available, it will be impossible to determine true mortality rate figures. It'll be GIGO, sadly.