Google has rolled out Android Pie to Pixel devices, and Essential managed to get an update out on the same day. A few OEMs like Moto and HTC have offered some insight on what they're updating. Today, you can add Sony to the list. It says updates are coming to devices in XZ2, XZ1, and XA2 families. Some of them might be here sooner than you expect.
According to Sony, the Pie updates will begin in November for the Xperia XZ2, XZ2 Premium, XZ2 Compact, Xperia XZ Premium, XZ1, and XZ1 Compact. It doesn't say which of those devices will be first or how long it'll take for all of them to get Pie, but the XZ2 family will probably be first. Not only is that Sony's current-gen hardware, but it launched with Oreo. That means Treble should speed up the process on those phones.
Also on the update list are the XA2, XA2 Ultra, and XA2 Plus. These budget phones are a lower priority for Sony, so the OTAs won't start rolling out until early 2019. The XA1 family appears to be stuck on Oreo.