I'm sure the regrettable events of that time did involve the experimental as well as a terrible necessity to do something and to my mind terrible as it was it was to my mind the only option available at that time and it wasn't in totality wrong doing by the Americans that caused these events and it really gets up my nostrils when it's always, 'how wrong of the Americans', always gets front seat.
I agree with you - almost completely. I think that, as you say, the Hiroshima bomb was "the only option at that time". My understanding is that its use and the immediate aftermath virtually paralysed the Japanese high command into total inaction and because Japan did not surrender immediately, Nagasaki was bombed.
It has been suggested that the Americans should have organised a demonstration of the atomic bomb on an uninhabited island rather than drop it on a major city, but the evidence suggests that Hiroshima had been selected as a suitable target some time before. It is enclosed by a ring of hills and the effects of blast and radiation would be contained. It was continually spared when other cities were subjected to fire bombing. Nagasaki was not a prime target and was only used because preferred targets were obscured by bad weather.
There is a very beautiful animated film, available from Amazon, entitled
In This Corner of the World which is about ordinary Japanese people living in the Hiroshima area during World War 2. I highly recommend it.
But - as I said before - what has this to do with COVID-19?