Not many device manufacturers use ultrasonic fingerprint scanners. This is probably because of the higher cost compared to optical sensors. Samsung is famous for using ultrasonic sensors in their flagship devices. Most recently, Huawei was seen filing a patent for an ultrasonic fingerprint scanner.
Huawei does this because of ultrasonic sensors because most of these sensors in the market are under Qualcomm patents and Huawei is not allowed to deal with this brand. Sensors supplied by Goodix that are also used by many manufacturers also use Qualcomm patents.
What differentiates Huawei's ultrasonic sensor technology from Qualcomm's is its construction. Huawei will use another stacked electrode design along with a piezoelectric layer and an array of electrode pixel units. This sensor is claimed to be able to send and receive signals to obtain fingerprint information accurately.
With Huawei already having its own sensors, they can continue to make various products on their own without having to rely on other companies. Who knows, Huawei may also market their sensors to other device manufacturers as well.