GCP startup (GFS) credits cover first-party Vertex AI (Gemini + self-hosted open models) but NOT third-party partner-MaaS (Claude/Llama/Mistral)

When planning LLM workloads on Google Cloud / Vertex AI funded by Google for Startups (GFS) Cloud Program credits (or the $300 Free Trial credit), it is unclear which models the credits actually pay for. A common and costly assumption is that any model reachable in the Vertex Model Garden — including Anthropic Claude, Meta Llama, Mistral, xAI Grok — draws down the credits because you call it through Google's own Vertex endpoints and Google issues the invoice. It does not. Picking a partner model for a credit-funded pipeline silently bills real dollars, while the equivalent first-party or self-hosted path would have been free against the grant.