Google will release stable Android 16 in June or July this year, meaning the upcoming OS update will arrive earlier than usual. This means that other smartphone makers will deliver the upgrade to their eligible devices on time. Hence, Xiaomi has started the Global Android 16-based HyperOS 2 public preview ahead of the stable release.
Xiaomi was among the companies to release stable Android 15 after the official announcement by Google. They are working to roll out Android 16 at a record time this year, with the beta preview now ongoing. Initially, the beta program was limited to Chinese users, but we knew it would not be long before Global users started getting it. However, only two devices are eligible for the beta preview.
Details of the Global Android 16-based HyperOS 2 public beta

Xiaomi has released Android 16 beta builds for the Xiaomi 15 and Xiaomi 14T Pro. The same duo that received the upgrade in China. Usually, these updates are exclusive to developers, but you can install them on your device. You can access the Recovery ROM via the source link, and you can start using it immediately after flashing.
However, you might experience some glitches since Android 16 has yet to adapt to HyperOS 2. Overheating is another issue you might face, and hence, we do not recommend installing it on your daily driver.
How to install Global Android 16-based HyperOS 2 public beta

Interestingly, you can install the build via the Recovery method, but somehow you will lose all your data. Before proceeding, ensure you backup your files.
To upgrade, you must be running the latest HyperOS build on your Xiaomi 15 ( OS2.0.109.0.VOCMIXM) and Xiaomi 14T Pro (OS2.0.103.0.VNNMIXM) or higher.
- Download the Fastboot ROM here: Xiaomi 15, Xiaomi 14T Pro.
- Move the ROM package to your phone’s storage.
- Head to Settings>About phone>>Tap OS version. Keep tapping until you become a developer.
- Go back to Settings>About phone>>Click the system icon>>Tap the three dots at the right top corner>>Select Choose update package. After choosing the correct package, the device will verify the ROM before the upgrade starts.
If for any reason, you want to go back to a stable ROM after installing Android 16 beta, Xiaomi has provided a guide via the source link. There is also an option to flash the build via the fastboot method, but that requires unlocking the bootloader. I doubt anyone would want to go through the stress when they can flash using the Recovery method. Nevertheless, there is more information on the source link.
source: Xiaomi