I know Halloween parties are probably still off the table: indoor crowds of people eating, drinking, and exchanging other fluids in small houses and apartments.
But what about trick or treating? Assuming everyone wears a mask, which isn't even unusual for Halloween, it's primarily an outdoor activity and all the candy should be prepackaged until the kids get home. Sure, it'll involve small groups of kids and adults traveling together that aren't in the same household, but if you live in area where they've already reopened schools then that'll already be happening on a larger more regular scale. All of this is assuming you aren't in a high risk household.
Oddly enough Trick or Treating could be a huge bump towards community organization.
The entire premise of Trick or Treating in the U.S. is one of strict consent - if you are participating you leave your door light on and if you're not you turn your light off.
It's almost trivial to imagine at least some houses in the neighborhood being fine with people coming to the door for candy. And if that's the case, then people will absolutely walk around the neighborhood for that candy.
So all that's left is the desire for physically stopping that with force if necessary (i.e., through the police). So it sets the stage for a ton of instances of "go away we're being safe here" and I would like to see that.