Lyria 3 Pro Preview and GPT Audio are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.
Lyria 3 Pro Preview, from Google, has a 1,048,576-token context window and is priced at $0.08/song on OpenRouter.
GPT Audio, from OpenAI, has a 128,000-token context window and is priced at $2.50/M tokens input, $10/M tokens output on OpenRouter.