Elliott Hughes, Google software engineer updated 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. If there was an update available, the button would download it. However, this feature still isn’t working.
According to Hughes, the bug that broke this feature will be fixed in early 2018. 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.”
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.
This error has been fixed internally. 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.