Updates to Android 8.0 Oreo are slow to arrive. However, this weekend saw users in ZTE's US beta program receive Oreo software, and HTC announced that sprint has approved the Oreo update for the U11 on their network.
https://www.notebookcheck.net/ZTE-and-HTC-bringing-some-Android-8-0-Oreo-love-to-the-US.279644.0.html