Yes, that’s a thing. It’s like onion powder’s sophisticated cousin who went to art school. Use ½ teaspoon of shallot powder for every 1 tablespoon of fresh shallot the recipe requires. It won’t give you texture, but the flavor is legit.
One surprising science bit: shallot powder retains more volatile oils than fresh after a few months. So your backup is actually more concentrated. Use less, or your sauce will taste like a perfume counter.