You want to study the people & problems you're targeting to the point that you become the expert they're trusting for advice about the problem. This is hard, but not that hard - minimum viable expertise is a thing as well.

For example, not everyone who uses email as part of their hiring process has spent an enormous amount of time studying how to improve contact-to-interview conversion rates. Specializing on this & studying across N people who are a close match for your target customer can quickly give you working expertise on the problem, because everyone else is worrying about 10 other things at the same time when working with it, while you can go deep on that one thing.

Then based on your understanding of their workflow & what ought to generate value (as obtained by talking to those people in a learner mode vs. a sales mode), you generate a hypothesis and test it. If it actually helps deliver value, and the problem actually matters, and you actually understand these people well enough to get them to trust you...congratulations, you might have yourself a viable product.

For the above example, you need exactly zero unique software to pull this off. You can start as a completely manual service with direct sales only against the people who you think will be most likely to buy. Give yourself the easiest win conditions you possibly can, requiring the least time and investment. Then, build on that, add automation as appropriate and test that the value is still delivered, try to scale, etc. - but start with the scaleless version, it ships easily and then you have actual customers who are paying you.