How do you know if it's open source? Well if it's called something like "huggingface" or "redpajama" there's a very good chance it's made by people who have no marketing department. So good odds it's free.
ChatGPT is pretty crap branding too, for the record. They just somehow managed to mainstream it. All the LLMs after it try to have cooler names (Bard, Copilot, etc.) but the kludgy first name is still better known.