Okay, so I'll get Pro to try it.
I subscribe.
No gemini 4.
The most generous reading I have is that it's a mistake. But I also downloaded the PC app, and now I really wonder why I did that, it seems to offer nothing beyond the web experience and also doesn't even know its a local app. (When asked about its capabilities it always responded with reasons pertaining to it being a web app.)
However, my experience with the gemini, jules and antigravity apps was awful. So it is difficult to pin that on the model.
I wanted it to give me a proper comparisson for VPSes or server options and it took so much babysitting and it couldn't produce reliable pricing information or visulalisations.
EDIT: Okay, the AI plans page claims under pro - "Expanded access to Gemini 4 Argon in Google Antigravity." So maybe it is just a matter of it rolling out. Though Google has a long history of serious confusing and misinformation on those tier descriptions.
EDIT2: And they changed it again, and now it is explicitly excluded from antigravity for Pro users.
I'm not going to 5.5x my subscription cost without being able to try it out first. To be fair though, I'm not going to 5.5x my subscription cost anyway, as my current usage would not warrant that! But that doesn't change the validity of my prior point.