Can I use lye as a leavener instead of baking soda?
I got a pretty thorough answer to my question on the Chemistry sister site to this one.

https://chemistry.stackexchange.com/questions/43896/can-i-use-lye-as-a-cooking-leavener-instead-of-baking-soda

In short, lye, while caustic, will not create a chemical reaction producing CO2, which is what baking soda does during leavening. So lye is at-best an inferior leavening approach, and in most cases, won't work as a leavening ingredient at all.