Ironically, OpenAI would be trademarkable because they're not open.
> OPEN describes a feature of the services provided by applicant, in that applicant provides a "public node" that is accessible to anyone and allows users to interact with the blockchain network. See attached from opennode.com. Thus, "OPEN" is descriptive of the applicant's services, in that it conveys the open and public nature of the node that the applicant provides.