Is there a way for me to make it so that when someone creates a digital asset in unity, the “Input Type” is “HDA” by default instead of the usual “UNITY_MESH”?

Unfortunately not at the moment. Do you have suggestions as to how you'd want to do that? Perhaps could do it via a prefix on the name? (e.g. hda_myinput or mesh_myinput)?

Got it. Using prefix on the name sound like a great solution.