Essential is currently offering a beta release of Android 8.1 Oreo. If you've got an Essential Phone and you'd like to try the beta, hit the Essential's developer site link below, select the over the air option near the bottom of the page, and fill out the short form with info like your name, email address, and device serial number. The beta will then be automatically pushed to your device within 72 hrs.
Source: Essential Developer Site
Essential has released the long awaited Android 8.1 Oreo in the form of a beta. Previous beta testers for Android 8.0 Oreo will get an over the air update to Android 8.1 Oreo, if you're not currently enrolled as a beta tester Essential has add a link to side-load the new software on its website linked below.
What's new with Android 8.1 Oreo on the Essential Phone? Essential has add dynamic icons for the calendar and clock apps, and the most important fix of all is said to squash the "slow scrolling jitter fix."
Essential also says that the Android 8.1 Oreo update comes with Google's latest February security patch, making it the first company other than Google itself to push the security patch to its devices.