Individual executives and spokespeople
Your second market and a genuinely separate one, as your own work with an executive spokesperson shows. The buyer is a person rather than a company, the budget sometimes sits with them and sometimes with their employer, and the decision is personal. Stated plainly: this group is not enumerated in any register, anywhere, which is exactly why it stays open.
Who signs: the executive themselves, their chief of staff, and the company head of communication when the company is the one paying.