ARM shipped it as a standard feature of Cortex cores significantly after it was added as an ISA extension. MediaTek and Exynos provide it and Snapdragon is approaching shipping an implementation.
Google set it up for usage on Pixels, and then later Samsung and others did too. Pixel 8 was the first device where it was actually usable and production quality. GrapheneOS began using it in production nearly immediately after it launched on the Pixel 8.
Nice to hear it’s already in use in some forms.
And of course it seems pretty obvious that if this is in the new iPhones it’s going to be in the M5 or M6 chips.