When I buy the Moss NFT, am I buying the actual land or am I financing protection of the forest?

You are buying the actual land with a firm commitment of preservation. This is NOT a financing vehicle or a game card for conservation of the forest (“buy this piece of art and the money will go to preservation”).
Of course, as more people buy these NFTs and corresponding forest areas with the intent to preserve, more and more people will participate in the formation of a “Green Wall” of protection for the Amazon.