OpenAI, Inc. is a company, and it owns other companies including OpenAI Holdings, LLC and OpenAI Global, LLC. https://en.wikipedia.org/wiki/OpenAI

>In May 2025, the nonprofit renounced plans to cede control of OpenAI after outside pressure.

Regardless of non-profit shenanigans, OpenAI is an entity. GPT is a type of LLM, which is not specific to OpenAI, other companies use this as well.

The nonprofit is OpenAI, Inc., a company: https://opencorporates.com/companies/us_de/5902936. Look at how many times the word "company" is used in the Wikipedia article.