I'm not an expert but since Grim Hollow is a 3rd party publication not from WotC, I'd guess that it will not end up in any official organized play events like Legend of Greyhawk or Adventurers League.
If you are looking for more info on Grim Hollow. It appears to be made by Ghostfire Gaming. It also appears to be available on D&D Beyond.
Anyone know if there are going to be any more of these (debuted at GenCon)? Anyone know a good site to find out more info?
I'm not an expert but since Grim Hollow is a 3rd party publication not from WotC, I'd guess that it will not end up in any official organized play events like Legend of Greyhawk or Adventurers League.
If you are looking for more info on Grim Hollow. It appears to be made by Ghostfire Gaming. It also appears to be available on D&D Beyond.
https://ghostfiregaming.com/grim-hollow/
https://www.dndbeyond.com/sources/dnd/ghpg