Harare for sure. Dubai is overnight I was told.Do the Dubai and Harare airports offer PCR tests that quickly? If so, that sounds good.
Don't forget this is February. My trip starts on July 28th, so I am sure things will get even faster between now and then. In regards to testing on the way there I think I will give myself a bit of a leeway by having two separate outfits do the testing. If one hits a snag in a timely delivery of results I will have the other test as backup.
Heck, by then a vaccination record might be sufficient instead of a test. One can only hope.