MIUI code has revealed that an upcoming Xiaomi device, expected to be the Mi Mix 4, will offer ultra-wideband support. That device will be the first phone by Xiaomi to do so, joining an elite lineup consisting currently only of the Galaxy Note 20 Ultra as well as the iPhone 11, iPhone 12, and Galaxy S21 series.
https://www.notebookcheck.net/Mi-Mix-4-tipped-to-join-the-ranks-of-the-iPhone-12-and-Galaxy-S21-series-with-ultra-wideband-support-as-it-hits-TENAA.552648.0.html