I found it almost impossible to find commercial listings online. And of the ones that were, several were listed wrong.
Is the area you are looking in near where you are? My wife and I went driving around a couple weekends looking for shop spaces that were available. Wrote down what we saw then searched online. That usually came back empty so we called the numbers to get the details.
Eventually we found a few promising locations and made appointments to see them. Found a shop that was just about everything we were looking for, and it's only 6 miles from home.