I have not bothered reading this thread, but I did immunology research in an earlier life.
First, herd immunity is the goal of immunization programs, not a strategy. The idea is that so many people have acquired immunization that the few people who, for what ever reason, cannot be immunized Are unlikely to be exposed.
Herd immunity did not stop polio, small pox, TB, common cold, Ebola or any other disease. There is a natural background level of diseases in a population, where people who survive the infection are immune and cannot pass it on. To get there a lot of people have to get sick and many will die. Most (90%) Native Americans were killed when European diseases reached the Americas because they lacked any immunity to those introduced diseases. Europeans were more immune than the indigenous people, but it didn’t stop them from becoming infected and some dying.
If you are traveling into a country and you are not immunized, you are just asking Mr Darwin to thin you out of the herd. Waiting for Darwin to solve the Covid crisis is not realistic.