There is no evidence that wearing masks would have saved every person you are talking about. But what I do know, if your folks were in charge nothing at all would have been done. Again, Biden didn't even approve of a travel ban until April... 3 months after Trump reacted Biden finally understood that banning travel from an infected country could stave off deaths. But he doesn't own his stupid, he has you to pretend it didn't exist....
They, your heroes, weren't wearing masks, they were going to Chinatown and pretending that Trump's travel ban made people afraid of Asian folk (no evidence, not one thread of evidence and just.. not true). Another problem, there were not enough masks here in the US for that to have happened... seriously, not even close. Running around and saying "xenophobic" is not a plan, didn't help, and was trying to undermine the single largest thing that could be actually done at that time to stave off many infections.
What I do know:
If Biden was in charge we would have had many, many, many more infections...