The majority of investors that I've spoken to about this see it as a negative, but I do think that those who are willing to embrace the changes will reap some of the benefits that you touched on in your OP.  

I am leaning towards Savannah mainly because it’s a great city for tourism but not sure if I should still consider that a factor due to COVID.

We have never been in Italy or Sicily during the High season of tourism.  

The best resources for this question are going to be in regions where the ADU has been embraced as an innovative way to create more places for people to live: the Pacific Northwest, specifically Portland, are the key players here.California is not too far behind because the state has made it much easier to permit an ADU through laws, including the latest in early 2020.The basic answer to the question is a permitted ADU should add 20-30% to the value of your property.

The area was busy and seemed to be doing very well for tourism.  

Embrace the learning curve, keep connecting with others, and don't hesitate to ask questions.

I chose the Smokey Mountain National Park area due to it's long history of tourism and positive attitude towards short term rentals.

I still stay in touch with my friends in the area, and so sad how much your country got impacted by the loss of tourism revenue.

So, visitors are fine and they keep coming back and retirees keep moving to Mexico.One thing to understand is that the drug cartels have no interest whatsoever in killing the golden goose of tourism, which would decrease their drug sales.

Economies that are relatively new and/or heavily based on tourism/recreation or other industries that rely on disposable income.Other than my NYC example above, why do you think supply will increase once we're on the other side of COVID?