I'm using Sign in with ChatGPT and then Codex App Server protocol for my desktop app:

https://github.com/cubacadabra/studio

https://github.com/cubacadabra/studio/blob/main/src/codex.rs...

https://www.youtube.com/watch?v=bTawLd5r2mw

https://learn.chatgpt.com/docs/app-server