Use a harness that doesn't lock you into a moat, like OpenCode.
FWIW Claude Code works with OpenRouter so you can use any model.
Codex is open source and lets you use any model https://learn.chatgpt.com/docs/config-file/config-advanced#o...
Codex CLI is open source too. I don't think there is a difference.
Can't use a claude code subscription in another harness though
You can use Codex with any endpoint compatible with OpenAI Response API[1], like llama.cpp.
[1]: https://unsloth.ai/docs/basics/codex