Full-song generation is available in the Gemini app, Google AI Studio and the APIs, where Google has released Lyria 3.5. It's the same surface set Google used for its recent Gemini model drops.
Google calls it an "advanced, full-song generative model with enhanced audio fidelity and vocal clarity, optimized for precise prompt adherence and rich, cohesive musical arrangements". The model first shipped in Google Flow Music on July 29.