With this json you can access the archives for every month on my chess.com account: https://api.chess.com/pub/player/gm_salzi/games/archives (Just replace gm_salzi with any other username)
The list of urls are the archives with the games you played. The data you want is the pgn section of the jsons of the archives.
I was thinking on using this API to create a report of the strengths and weaknesses overall of my games (Maybe I can make this open source too) and I know it can't make moves but can it get game pgns?