Let me give you the complete etymology of this compound slang word.
It is correct that the first part of this word, POG, refers to the
abbreviation for "play of the game". {Source: Wikipedia}
And so hence, Pogchamps would
technically (and was probably intended to) refer to someone who is so good at a game that they always get POG.
However, gradually, this term has cultivated a new meaning for members of the streaming website Twitch.tv.
Now, Pogchamps exists as a versatile Twitch emote used to convey something or someone that is awesome and cool.
The first part of this term, pog, is also commonly used as an adjective or
interjection to convey feelings of shock, excitement, and delight.
There is also now a online Chess tournament called PogChamps.
Friend 1: Omg look at my new
gaming PC my parents bought me!
Friend 2: Wow that's so pogchamps!
Friend 1: Hey
guess what?
Friend 2: What??
Friend 1: I just hit over 10,000
subscribers on my YouTuber channel today!!
Friend 2: Dang you're a pogchamp!