This would be a great addition to Cubasis. Create or save new projects, edit existing projects directly to an external SSD.
The video editing app, LumaFusion has this capability. It requires a very fast USB-C SSD, and I believe it must be formatted as Mac APFS, but the folks on their FB user group talk about it and use it all the time.
If this could be implemented in Cubasis, it would be a fantastic addition for users held back by limited iPad storage.