Python Error - TypeError: item 1 in _argtypes_ passes a union by value, which is unsupported
It seems like there is simply no support currently for using gym+pyglet in python version 3.7.6+.
The pyglet error is fixed in 1.4.9+ but gym is currently not compatible with those versions.
Still it is possible to simply downgrade python to 3.7.4 and everything works fine as it is supposed to do.