Gemini 3.5 Flash Lite and GPT-6 Astra Pro are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.
Gemini 3.5 Flash Lite, from Google, has a 1,048,576-token context window and is priced at $0.30/M tokens input, $2.50/M tokens output on OpenRouter.
GPT-6 Astra Pro, from OpenAI, has a 1,050,000-token context window and is priced at $10/M tokens input, $50/M tokens output on OpenRouter.