Until recently, I've been thinking of the extra love tap from Polearm Master as basically no better than dual wielding a dagger, but now I found out that not only does it benefit from ability bonus to damage, but I saw people claiming that, since you're attacking with a two-handed weapon, you're entitled to the rerolls of Great Weapon Fighting
When you roll a 1 or 2 on a damage die for an attack you make with a melee weapon that you are wielding with two hands, you can reroll the die and must use the new roll, even if the new roll is a 1 or a 2. The weapon must have the Two-Handed or Versatile property for you to gain this benefit.
... or the ability to power attack of Great Weapon Master ...
Before you make a melee attack with a heavy weapon that you are proficient with, you can choose to take a -5 penalty to the attack roll. If the attack hits, you add +10 to the attack's damage.
And, bizzarely enough, I can't think of a reason these two wouldn't, since both the Halberd and the Glaive have the Two-handed and Heavy properties... Is this right?