I just want to mention here as a datapoint, for my book tour I asked that the stores request that people wear masks, even if they couldn't require it. (I asked that first because I would be in a lot of airports and didn't want to pass anything along, then when I got the cancer diagnoses it seemed an even better idea.) And attendees did wear masks, in Houston at Murder By the Book, in Georgia at Eagle Eye Books, in Cincinnati at Joseph-Beth, at the St Louis and College Station, TX, libraries.