Shawneda's advice appears very good, helpful and insightful. No experience in book publishing here, but about 40 years in marketing communications (PR, branding, advertising, event, etc) about half as a consultant and half as manager in corporations hiring consultants and agencies.
Two areas to further think about and explore are (1) positioning yourself and (2) the consultant/agency relationship.
1) Totally agreed that you are the brand, for all the reasons you mention. Your pitch is all good, but could use stronger differentiation, a more salient value proposition -- what unique attraction are you bringing to the market? You have those assets on Medium. Building upon them, incorporating your aspirations could well make you stand out. If philosophers are like athletes, the market wants a Tiger Woods or a Caitlin Clark.
I consulted for a woman with a psychology degree who was working in special ed at an elementary school. She was trying without success to get a paper published on her experience at the school. I found her unique attraction on page 10 of her paper! She needed to get this loud and clear on page 1. She did that, and got published pretty quickly and has moved on in her career. A good consultant can help with this, but the inspiration can only come from inside you.
2) Both agencies/consultants and clients tend to view each other with suspicion. At the end of the day, both sides are in it to make money, and if there is no relationship established, both sides look at the other side as a potential ATM machine, or a sheep to shear.
What works well is when both sides are excited about the mission for its own sake, and they feed off each other's enthusiasm, and how each other brings their own special strengths to the table. This is a key reason why Steve Jobs was so successful. In his own weird way, he was a motivator.
You might well have been doing this already, but one good question to ask potential PR people is "tell me about your biggest successes and failures, and what did you learn from them?" Hopefully that prompts a lot of open, revealing discussion, with you sharing your aspirations. This is a path for you and them to see how a successful, fulfilling relationship could be formed and take everyone's ambitions to the next level.
