When did they use an incomplete, pre release, version of Apple Maps for tech journalism marketing?

They didn’t. So not a counter example.

Isn't Apple known for demoing pre release versions of everything on stage?

I think that fairly counts as a "marketing ploy"? Apple is so good at it that folks that folks don't even realize what is happening.

https://www.youtube.com/watch?v=BVthxoS6H9k

That’s when they announce it, yes. That’s usually they only time they do that.

Compare with Meta: pretty sure this is the 3rd “sneak peak” cycle on this hardware in the last couple of months.

No, it's not. It's different technologies each time that their research lab is working on at the moment.

I wouldn't call that pre-release by the standard definition.

The product is complete and it's just about ramping up production and sending stock to retail stores.