@ElsieD As you mentioned Pinsa, I was recently given a 400gr package of Ruggeri Pinsa dough, the instructions mentioned dried sourdough
https://www.ruggerishop.it/products/farina-per-pinsa-romana . So, I think it can be used as a single use leavening agent?
Now the instructions on the package and the website did vary significantly in hydration ( 80% on the website and 70% on the package).