I have been working on a project that is built off of Cloudflare's pingora project - https://sbproxy.dev. This provides all of the features of a LiteLLM, but can also support your API traffic too. I worked on the edge infrastructure for Walmart, and took those learnings and build a fully open source gateway.
Take a look - should be able to address your needs.
Take a look - should be able to address your needs.