Google said last month it'd make Recorder available for older Pixels. On Thursday, it updated the app, which should now pop up in the Play Store for other supported Pixels, namely Pixel 2 and later devices. However, it doesn't seem to work on the original Pixel -- at least not officially.
As is the case with many other apps, it might run just fine on other Android devices. Some users have been sideloading the Recorder APK to their phones. The app crashed when some of them tried to launch it, though Android Police suggests the update might have resolved the issue.