Touch Bär uses undocumented, private API to add a Touch Bar button to the Control Strip on the right-band side of the keyboard.
DFRElementSetControlStripPresenceForIdentifier(NSString *, BOOL);
DFRSystemModalShowsCloseBoxWhenFrontMost(BOOL);
+[NSTouchBarItem addSystemTrayItem:]
+[NSTouchBar presentSystemModalFunctionBar:systemTrayItemIdentifier:]Alexsander Akers, me@a2.io
Touch Bär is available under the MIT license. See the LICENSE file for more info.