The new Sony FE 400mm f/2.8 GM OSS Lens(Amazon/B&H/Adorama/Focus/WEX/Park Camera) now already released in US, and will be in stock within next few days at Adorama.
Here is first unbox video of this lens by Patrick Murphy-Racey:
And test by Jason Vong for Sony a9 + 400mm f/2.8 G Master at Miramar Air Show 2018: