As long as there are some more or less consistent rules of the game, what lederhosen suggests might be a good solution. I.e. no travel restrictions, quarantine, tests or whatever between countries with a similar risk level. And said risk level is based on the choice and implementation of a specific approach. Zero COVID countries, like Taiwan, Australia and New Zealand, form a travel bubble among themselves. Countries with high vaccination levels, where risk is still somewhat higher than zero but a lot lower than elsewhere, form another bubble. And the remaining countries continue with the present status quo, changing rules and restrictions every other day until they do whatever it takes to join the "COVID-safe" club.