I assume that Thought Crime will be formalized eventually anyway so I am actively building alternatives to OpenAI.
Check out this post where I provide more details on the project & how we could horizontally scale by letting plebs rent out their API keys on StartOS devices: #418051
As far as API goes there is not an explicit API but it is built on the NIP-105 spec which formalizes how services are discovered over nostr, and requested via clients.
You could easily find endpoints by scanning wss://nostr.kungfu-g.rip/ and just start using the GPT one of those.
If you're interested DM me on nostr and I can provide more support & tooling.