The difference between the NFL and MLB is that the NFL will just play through COVID.
I think the difference is that the structure of the Sunday/Monday games will make it easier to screen and react. With everyone playing on the same schedule and once a week, I think there is a better chance to have everyone take a test on Friday or Saturday. Positive and you're out, but the game continues. Might need a second test during the week to prevent outbreaks.
The big thing is that you need a plan. MLB had 170 pages talking about spitting and showering, but nothing about how to react. Hopefully the NFL takes note of how quickly that turns into a **** show.