Interesting but when I tried it, I couldn't figure out the billing model because it's all connected to Google projects, and there can be different billing things for each of them.

Each thing seems to have a bunch of clicks to setup that startup LLM providers don't hassle people with. They're more likely to just let you sign in with some generic third party oAuth, slap on Stripe billing, let you generate keys, show you some usage stats, getting started docs, with example queries and a prompt playground etc.

What about the Vertex models though? Are they all actually available via Google AI Studio?