system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] how would planets without flora like Tatooine and Hoth have breathable air?

Admittedly I don't know much about this sort of thing but I thought that without plant life, there wouldn't be enough oxygen to support animals.
gpt
Most oxygen production comes from single celled organisms like algae. There is probably a desert algae that uses a brown pigment to collect sunlight. If moisture vaporators are economical, no doubt single celled organisms have figured out how to extract the required water from the air, or maybe even break down sand to extract the required components.