Sourdough baguettes from tartine - without instant yeast?

For the last few years instant yeast was mostly an afterthought, as I’ve focused on my sourdough. About a month ago I started baking baguettes based on Chad Robertson’s recipe in Tartine, which uses a poolish made with instant yeast alongside my standard leaven. Finally, just as I was dialing them in I realized that my tiny, back-of-the-refrigerator stash of instant yeast needed to be replenished. Of course, I soon discover that all these new homebound bakers have pretty much carted off all of the instant yeast in my local stores.

This got me to thinking - is there a way to recreate the sweet, yet flavorful combination of leaven + poolish with just naturally occurring yeasts? pate fermentee is just “old dough”, right? Is this just another sourdough culture that needs different handling but can be used from one bake to the next?

I know I can change the timing of my sourdough refresh to reduce the acidity, but baguettes are tricky and im trying to avoid wasting flour as well. Before I go down this path, is there a better way to get the results that I want, or have the best (sweet) baguettes always been made with instant yeast?