Vivo had already demonstrated this feature last year with the Apex 2019 concept phone, so we know that the technology exists. It is unclear as to when it will make its way to a commercially available smartphone. The number of variables at play here is immense, so it wouldn't be surprising if it takes Xiaomi some time to iron out all the kinks.
Xiaomi working on all-screen fingerprint unlocking technology
Biometric authentication has come a long way since its humble origins in the capacitive fingerprint sensor. Face ID, ultrasonic sensors, and under-screen optical sensors have since taken precedence and are now present on almost every modern-day smartphone. Xiaomi wants to push that envelope even further and is reportedly working on some revolutionary fingerprint unlocking tech.
According to Twitter user StuffListings, Xiaomi is working on tech that allows the whole screen to function as a fingerprint sensor. It essentially lets you unlock your phone by presenting a registered fingerprint anywhere on the screen. Xiaomi seems to have made quite some progress in this regard, based on the images linked to the Tweet.