Sorry, I watched it last week and never heard it mentioned so did some digging.

>While Avatar: The Way of Water shared many similarities with its predecessor, the mineral wasn't mentioned once.

https://screenrant.com/avatar-2-unobtanium-story-missing-sequel/

Agree 100%. It also annoyed me that they are now only there to get fancy sperm whale oil (no mention of unobtanium).
I do think the vibrancy in his world building is amazing and not to be underestimated in its impact on reception.

Yes, you will get some amazing ideas, guaranteed. Yet, somehow, when it hits the screen, it will be the same old shit.