An update for the Samsung Pay app contains code that explicitly refers to the "Beyond", which is the codename for the Galaxy S10 series, as having an in-screen fingerprint sensor. The new technology will reportedly not feature on the Galaxy S10 Lite, also known as the S10E, as this will have a side-mounted fingerprint sensor instead.
https://www.notebookcheck.net/Samsung-seemingly-confirms-that-the-Galaxy-S10-will-have-an-in-screen-fingerprint-sensor.396781.0.html