Had COVID-19 started in the US under Trump's watch...

[Skill and Chance]

Trump could shut down air travel to/from Texas and put roadblocks at state borders, but anything more than that would be up to Greg Abbott.  With the real COVID, he started off proactive in March/April, then went libertarian in May and then got proactive again in late June and July (really, one of the most proactive summer wave responses in the country for an R governor in a Trump state). 

If this scenario happened, I think he would start off super aggressive (especially with the opportunity to play himself off against the Dem mayor of Dallas) and have the national guard quarantine the Metroplex for a few weeks.  However, he would be anxious to declare victory and may lift the quarantine too soon.

[Skill and Chance]

If COVID had started in the US rather than China, the result would have likely been worse in the US than COVID was in China, but better for the world as a whole due to greater transparency.  The WHO for one thing would not have been as deferential to any kind of propaganda from the Trump Administration as it was to propaganda from China.

The world as a whole would be 10X better off with a pandemic that started in a country with free speech. 

[Skill and Chance]

Weird premise.  Zoonotic viruses (like COVID-19) originate in places where many, many people live in close proximity to a lot of animals.  A very high level of human/animal density is needed for zoonotic transmission of a novel virus.

Ehhh, Spanish Flu may have originated in rural Kansas.  I agree it would have been better to use, say, a meatpacking plant in Amarillo in the example rather than Dallas.