I (unfortunately) updated swiftkey to the latest version in an attempt to troubleshoot an issue I had, low and behold, a new copilot button has appeared!

(Ironically, I was trying to remove an @ key that popped up in an app which reduced the length of my space key by 1/3rd)

Edit: Disabling the copilot options in settings is necessary as they are on by default, disabling does not remove the button. Thanks to this post for reminding me to review settings after an update.. *unhappyface

Edit2: So I just discovered that that you can obtain several types of debug info by triple tapping on the version number in the about screen... That's nifty!