Please list this experience under "Volunteering" (On LinkedIn, go to your profile, Add profile section, Additional, Add volunteer experience).
Please do not list your lead role under "experience" (this is where you current/previous jobs are).
List it under "Cohere" company - we recommend mentioning Cohere Labs in the volunteer title or description. For example, "Cohere Labs Open Science Community Lead."
You are encouraged and welcome to mention which group you are a lead for (ie. Reinforcement Learning, Computer Vision, etc).
Feel free to write a detailed explanation of what you do - ie. host weekly paper readings, create presentation decks, organize/schedule guest speakers, etc.