Just checked in a Win 10 Gimp 2.10.14 and everything is there on the installation.
Not able to find the mypaint tool in the cluster of awful icons? You can get it from Tools -> Paint Tools -> MyPaint Brush
Still not there? Check that the brushes exist. Look in Edit -> Preferences -> Folders -> MyPaint Brushes and see if you can check that the folder in the path: ...something \mypaint-data\1.0\brushes exists. Again Ok on my installation.
Adding a tab in one of the docks, same as any other, Click on the little left pointing arrow and follow the "add tab" dropdown.
With the MyPaint tool options, click on the brush icon to show available brushes.
Not able to find the mypaint tool in the cluster of awful icons? You can get it from Tools -> Paint Tools -> MyPaint Brush
Still not there? Check that the brushes exist. Look in Edit -> Preferences -> Folders -> MyPaint Brushes and see if you can check that the folder in the path: ...something \mypaint-data\1.0\brushes exists. Again Ok on my installation.
Adding a tab in one of the docks, same as any other, Click on the little left pointing arrow and follow the "add tab" dropdown.
With the MyPaint tool options, click on the brush icon to show available brushes.