Hi,
Please enable possibility to swipe down from top when in portrait mode and swipe left from right hand side when in landscape mode to call android status bar (the bar with clock and icons). It is apparently built-in ability of android and on your version it’s disabled. It would allow in fullscreen applications to easily change front light settings, check the time, battery status etc.
Check in this video how it is done on likebook mimas (timestamp around 3:03).