Now that’s a hot take.

Your safest bet is probably an iPhone. Theoretically, any phone that supports both CDMA and GSM networks should work everywhere. I’ve used my unlocked iPhone 11 all over the world with zero issues over the last 4 years.

As others have said, 180 days isn’t guaranteed. It will likely be very difficult to change after the fact, and they’ll probably grill you about onward travel. This has been an issue for years and years now.