Years after the gopro 4 arrived, its nearsightedness became a real problem when recording the piano.  The low keys were sharp while the high keys were blurry.  It wasn't even known to be nearsighted until long after its eclipse duty.  

This method works on a 4, but it's 1 time only.  It chews up the plastic.  You can probably leave the inner ring attached, to have more plastic to chew.  A 2.5 mm turn got the high keys in focus & the low keys only barely softer.  Selfies definitely won't be as sharp.

While the lion kingdom got a 7 for its super smooth stabilization, it still uses the 4 for the gimbal & dual cam shots.  The 7 requires a robot to get cinematic stabilization but is sharp from end to end.