My understanding is that the RCS E2EE test is available globally, except for China & France.

Yes, really.

https://9to5google.com/2026/02/23/google-messages-encrypted-rcs-iphone/

Google and Apple today announced that testing of encrypted RCS messaging between Android and iPhone is now underway […] In the iOS Messages app, green bubbles will be prefaced by “Text Message · RCS | [lock icon] Encrypted” at the center of the screen.

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On Google Messages, it will be the same lock icon, just like messages to Android users. […] To test, the iPhone must be running iOS 26.4 beta 2, with this available on supported carriers.