How does the process look like for you to be able to reach and partner with relevant experts who would supplement you with Insights for that niche/domain?
It is likely that your advisory board can't always prove to sufficient at this and if you are a startup, you may not even have a formal & diverse advisory board. So what do you do in those cases?
How do you become an expert in your field? You work at it. You study it. Read relevant journal articles, go to school if you need to gain understanding required to read those articles, attend conferences, research over the Internet and find good sources, study, engage with many others and use their information to inform your point of view. Perform experiments rather than just trusting with others say. It takes about 2500 hours to become reasonably good at most things, at least to the point where you know enough to start to realize what you do not know. Your advisory board, if properly done, can flex to add/change people so that you can get short-term access to specialized experts. And by the way, this costs money.
What do I do? Exactly what I just told you to do. I have spent about 50 years doing it and will continue to do so to learn more about the next thing I do. It's the only way I know of to gain expertise. Knowledge, training, education, experience, and skills. Gained by working at it.