Back in September, a Googler noted that the “Check for update” button on Pixel and Nexus devices would work to offer any available OTAs for download. This has clearly not been the case in recent months, but it will finally work again in 2018.
Google software engineer Elliott Hughes updated (via Android Police) his original post detailing how the button is supposed to bypass the gradual rollout schedule by signaling to Google that a user has manually requested an update.
However, an issue in Google Play services “broke the feature again,” though it has finally been fixed. This issue was due to an “API incompatibility between the System Update code and the Checking code.”
The button is now working internally for Googlers, with the company promising to improve “the testing process that allowed this incompatibility to slip through.” However, due to end of the year scheduling, it will not be available to the public until next year with a future update to Google Play services.
This feature will work for Pixel and Nexus devices, as well other phones and tablets that use Google’s OTA system. It is conveniently not reliant on Oreo, only that upcoming Play services update.
UPDATE: a Google Play Services update after I posted this broke the feature again. (An API incompatibility between the System Update code and the Checkin code, if you’re interested in the details: bugs involving two separate moving parts are often the sneakiest.) This was fixed again internally, but late enough that it will be next year before this works again for non-Googlers. Sorry about that. We will also be improving the testing process that allowed this incompatibility to slip through.
More Info: 9to5google.com