Off the top of my head "flying vehicles" and "body preservation" are well-attested in many other cultures (Ancient Egypt; Mayans) that I'm 100% certain had neither. You are for sure reading too much into this.

> And even if it is hokum

I 99% believe that you think these things are real; I don't know if you're a von Danikenite, but you sure talk like one.

> If there is no evidence to either support or refute it

There is evidence that there's no evidence: we've been digging holes all over the world for centuries, looking for raw materials -- quadruply so, very recently, in the Indian subcontinent. If there was a civilization capable of supporting space-age technology, we'd've found it by now.