The Check for update button on Pixel and Nexus devices has in recent times become a redundant feature, which ends up annoying users who love to press it despite knowing that it doesn't really work. All that is set to change, for good, in 2018 when Google issues an update that puts the button to good use.
Back in September, Googler Elliott Hughes had posted on Google+ that the Check for update button had started working with updates getting shown on the smartphone once the button got clicked. But, unfortunately, a Google Play Services update soon broke the feature again. Hughes is back with an update on the bug and it seems 2018 is when users will finally get to put the button to use, as it has been fixed internally.
Despite a fix for the feature, Hughes writes that non-Googlers will only be able to use it by next year when internal testing gets completed. Hughes does note that as long as your device is running latest Google Play services, there won't be any requirement to sideload any newer OTA or factory image. This method also goes past the regular rollout scheme of Google, so even if there is 1 percent rollout done and 1 percent users have the update, clicking on Check for update will make that update available for your device.
He also says in the post that this update to the Check for update button is not just limited to Pixel or Nexus devices, and instead applies to others that use Google's OTA system. According to the Googler, this feature is not exclusive to Android Oreo. "The AOSP Settings app basically sends out an intent when you go into the system update section, and if you're using Google's OTA system, Google Play Services steps up and shows its UI," said Elliott Hughes in the Google+ post.