I would check out if Not Diamond (no personal affiliation) [0] fits your use case. They had a really interesting blog post recently where they open sourced their older model router [1].

[0] https://www.notdiamond.ai/features

[1] Blog - Routing on Random Forests - https://www.notdiamond.ai/blog/rorf

The best option I have seen for routing is LiteLLM. Worth a look.

try https://github.com/lm-sys/RouteLLM video: https://www.youtube.com/watch?v=mcZKQe2pUA0