Does =EVEONLINE.MARKET_ORDERS_STATS pull market data from the region as a whole (NPC and Player Structure markets) or JUST NPC Markets?

It pulls NPC structures and any player structure buy orders that are visible to the public endpoint.
It’s basically just

with the type_id restriction added to it.

Player structure can use the .MARKET_STRUCTURE_ORDERS_STATS function, but it requires a character to be logged in (for access reasons)