Baked baking soda for baking ???

I don't know if Baking would affect its rising power. Add a teaspoon of baking soda to a tablespoon of vinegar and see if it fizzes--if so, it still has some zip. But I also wonder if the flavor is affected by having been baked.
I personally would use it for cleaning; I have a container of it next to my sink to scrub off tea- and coffee-stains from cups, thermoses, and pots, using a dab on a damp sponge. Add a couple of Tbs into a teapot or coffee carafe--placed in the sink to avoid the mess, because you're making a science project volcano!-- and top with 1/2 c dollar store white vinegar. Wait till the fizzing subsides, then wipe the stains away.
I also use it like cleanser to scrub my pots and pans, and even the sink. Works on bathtubs too!
And I toss some down my drains if they're slow, and top with vinegar. The fizzing action gets rid of any nasties in the pipes without harming them, and freshens them as well.

I'm not 100% sure on the chemical legitimacy of this advice:

BUT since you bake the baking soda to make it MORE basic than usual, I would think if you used it as a leavener you might run into a time constraint. Baking soda leavens by reacting to acids, often buttermilk or lemon juice and you have to quickly get the baked good into the oven before the reaction fizzles out. So there's a possibility you could get the most cloud-like buttermilk cookies ever but I think there's a larger chance that the reaction will happen before you could get any batter to the oven.

But that's okay...since you took the time to bake the baking soda, I'd think only something special or complicated like more ramen noodles or pretzels/bagels would be worth it. The baked baking soda will last months so long as it's mostly airtight and in a dark place. And both ramen noodles and pretzels freeze well!