I would say "neither." If the yowie is real, it is not bigfoot. Similar, perhaps, but not same. No more than almasty or yeren. The similarity without sameness is suggestive of biological reality. Sameness would not be IF you understand evolutionary biology. There is no testable evidence for any sort of dematerialization of any sort, never mind rematerialiation, never mind preserving organization of structure and life through the process. Suggestions of similar processes shows lack of understanding of those processes, it amounts to word salad.
If yowie is real, likely they arrived in a manner similar to human arrival: over water in the geologically recent past when the sea levels were lowered by glacial ice on land. Or aliens transported them. Even that, ridiculous as it sounds, is far less "out there" and far more scientifically supportable than your suggestions.
MIB