FWIW I have spent a few years leading GTM strategy for startups, am consulting on marketing for startups, and thinking about getting back into a startup, so I'd be open to a conversation about what you're trying to do.

Fundamentally, marketing is about 2 things: awareness and engagement. Awareness is generally about socializing the problem, how current solutions fail, and what the gaps are, in a way that directly maps to your product. Each market is different enough that you have to appreciate the context: who has this problem? Do they know they have this problem? Have they budgeted for a solution (i.e. are they in-market or are you trying to convince them to spend money on it)? The classic b2b trap is everyone telling you it's a problem, but it not being enough of a priority that they actually spend time fixing it. That's often more indicative of a product problem than a marketing problem, but it shows up most in weak GTM. Validating that in your early GTM is key.

Similarly, engagement is context dependent, but I like to think of success as moving them to the next step of the funnel. Do they believe they have a problem? Are they looking for solutions? How are they going to make a decision about which to bring on board? What information can you offer to frame your offering in the best possible light vs. their other options (including no solution)? Build your collateral to that.