What can I make with just Flour, Water and Baking Soda?

What can I make with just flour, water and baking soda as the main i8ngredients?

Flatbread?

Irish soda bread

I would suggest bannock, though it usually has some lard in it.

Often it was formed into a ribbon and wrapped around a green peeled stick, and roasted around a fire.

Good article on the history of bannock:
https://thecanadianencyclopedia.ca/en/article/bannock

Bannock is usually unleavened, oval-shaped and flat. The version that we know today came from Scotland. In its most rudimentary form, it is made of flour, water, and fat or lard. Milk, salt, and sugar are often added, depending on the recipe. It is traditionally cooked by mixing the ingredients into a large, round biscuit and baked in a frying pan.

If you could convert the flour and water to sourdough, that would give you acidity to react with the baking soda (sodium bicarbonate) to make quick bread or crackers. A little salt and you might make real bread. If you had some fat then there are a whole raft of other baking opportunities.