Although the release date is not public yet, HTC has just confirmed that Android Pie will reach the U12+, U11+, U11, and U11 Life (Android One) handsets. The company also revealed that the timeframes will be announced in a timely manner, so it is rather safe to assume that the update will not arrive too soon.
https://www.notebookcheck.net/Android-9-0-Pie-confirmed-for-the-HTC-U12-and-U11-series-launch-date-still-unknown.322932.0.html