A good case study is Sweden. They remained completely open this entire time and although they have more deaths then most of the EU per capita they are decreasing in cases.
https://www.usnews.com/news/world/articles/2020-07-07/swedens-daily-tally-of-new-covid-19-cases-falls-to-lowest-since-may
The death toll relative to the size of the population has been many times higher than those of its Nordic neighbours, where authorities took a stricter approach, but lower than in some countries that locked down, such as Britain and Italy.
Health Agency data showed 14 new COVID-19 deaths were recorded on Tuesday, bringing the total to 5,447, more than half of which have occurred at nursing homes and among the elderly receiving home care services.