I upgraded my llm-gemini plugin to provide CLI access to Gemini Flash:

    pipx install llm # or brew install llm
    llm install llm-gemini --upgrade
    llm keys set gemini
    # paste API key here
    llm -m gemini-1.5-flash-latest 'a short poem about otters'

https://github.com/simonw/llm-gemini/releases/tag/0.1a4