Just a note that you can use opencode with their API gateway (they call it "zen") to get access to all the most popular models using a single account, including gemini. (Although this wouldn't have helped the author, since they wanted to try the Gemini CLI specifically).
I'm using opencode which I think is now very close to covering all the functionality of claude code. You can use GPT5 Codex with it along with most other models.