Google is progressing with Android 16, and you would expect other smartphone makers to be doing the same. With the Android 16 Beta 2 available for Pixel phones, Xiaomi has started testing the upcoming OS for the 14T Pro. It’s an internal test.
Xiaomi phones were among the first to receive the stable Android 15 update. With the pace at which the company is testing the upcoming OS, they will release the update before everyone. And should that be the case, the Xiaomi 14T Pro Android 16 will be the first to start rolling. That’s because the Chinese company has commenced internal testing of the latest T-series device.
Details of the Xiaomi 14T Pro Android 16 beta build

Xiaomi has limited availability to developers. Individuals will not access the ROM until the public testing starts in the coming weeks. We do not know what will happen, but given the progress made already, we might not wait much longer.
While I believe Android 16 will be based on HyperOS 3, the current build is built on HyperOS2.0.2xxx. We expect that to change before the final release.
Stable Android 16 timeline by Google

Google will reach platform stability this month. It will open up public beta testing for other smartphone companies. The stable release is expected in August, a few months before the release of Xiaomi 16. Given what has happened in the past few years, we expect the devices to debut with Android 16.
When will Xiaomi start rolling out Android 16 to everyone
It’s hard to say when Xiaomi will release Android 16, but we are looking at October. The same happened with the release of Android 15 but limited to the Xiaomi 15 series. They started rolling it out for eligible phones in December, and we expect the same with the upcoming OS. Perhaps it might be released early due to the pace at which Google is testing.