Pokemon GO has now enabled access to raid battles to you and your friends no matter where you are in the world.
As of July 15, you can call for backup even if your friends aren't in the same place as you. Here's how.
Pokemon GO: How to Invite Friends To Raid Battles
Once you're in the game and find a raid you want to jump into, tap the "+" button. You'll be able to invite up to five friends to play with you, and they'll receive a push notification if they have those enabled.
If someone invites you, you'll find the request in the "Nearby" screen, and there are no friendship level requirements, either. That means you won't have to grind friendship levels to be able to raid together, you can do it with anyone!
Here's hoping this change isn't rolled back after the current COVID-19 pandemic is over.