I heard mention on NPR this morning that the CDC says diligent handwashing can prevent 1 in 5 cases of respiratory illness ( I.e., flu and COVID-19). That didn't sound right, given the emphasis placed on this for prevention. But I just found the information on the CDC website.
https://www.cdc.gov/handwashing/why-handwashing.html
Apparently the main benefit is in preventing gastro-intestinal illness, where it can reduce the infection rate by 20-40% ( and up to 58% in immune-compromised individuals).
But for respiratory illness, the reduction rate is 16-21% (so actually less than 1 in 5).
I am not saying you shouldn't practice good handwashing hygiene, but don't rely on it to keep you completely safe. And factor this into your risk assessment when you weigh the pros and cons of canceling your trip.