What you need is a recipe desiged to use soda. You can't just throw
some in there and get the same results.... Or you can replace the
liquid in the recipe with a soda and experiment. You will still need to
use a leavening agent. I haven't tried or seen any of these do far, and
really have little interest in them... when there is a world of good and
simple pancake recipes out there in the recipe web sites and cookbooks
and magazines. The end result isn't going to be much different! When
it ain't broke.... don't fix it. {grin}

Yes, there are recipes for pancakes that call for pumpkin (Plain canned
pumpkim is pumpkin puree). And for applesauce. Both replace,
partially, the liquids in the recipes. The pumpkin pancake recipes also
usually include pumpkin pie spice or other similar spices... cinnamon,
ginger. And most using applesauce also use cinnamon.

You can add diced or thinly sliced raw apple to any basic pancake
batter... or canned apples, drained... again, usually adding some
cinnamon. Blueberries, cranberries (sweetened dried cranberries are
best for this use... just rehydrate them), peaches... the works....

You can find a wealth of such "fancy" (pretty much meaning any flavor
except the basic pancake) pancake recipes at the big recipe web sites...
or Google for them... or next time you are near a bookstore or library,
check some larger family type cookbooks. Many of these different
recipes yield excellent pancakes of good texture and flavors, so it's
worth poking around. Once you find which of these web sites fits your
tastes or level of how elaborate a cooking style (simple homestyle to
haute cusine, and even cuisines of different countries) you want to use,
you'll find a wealth of all sorts of recipes to play around with... and
you'll begin to see which types you can easily adjust or change
easily.... for all sorts of dishes.

Jo Wolf
Martinez, Georgia