How do you create a digital asset without the need for Houdini Engine; while retaining the proceduralism for the asset when importing ?

Not sure if I understand the question correctly. Without using Houdini Engine, there isn't really a way to load a Houdini asset into Maya. It's technically possible to write your own Maya plugin that uses Houdini's HDK directly. You can then use HDK to load Houdini assets into Maya. But you'd basically be writing your own Houdini Engine at that point, which is probably not what you want to do.