@Gattocaso the Polearm Master feat allow to use a bonus action to male a melee attack. The melee attack can be a Shove? yes
— Mike Mearls (@mikemearls) September 16, 2015
That wasn't an official ruling. It is incorrect.
— Jeremy Crawford (@JeremyECrawford) July 26, 2017
I thought Polearm Master feat allow a use of a bonus action to attack with the opposite end of the weapon only when taking a Attack action with a glaive, halberd or quarterstaff NOT another attack other than the opposite end of weapon.
Also I thought you could not attack more than once per Attack action unless you had the Extra Action class ability (Fighter) which allow for multi Attack actions which shove (takes an Attack action) could be one of them.