I have a system for this.
You have two problems, not one. You need to get useful feedback out of 100pct of people, and you might need more people.
To get useful feedback, distill your potential value proposition to one sentence. If you have multiple ways of saying it, make a couple. But one sentence only and write it down.
When you have someone from the correct category (target market) on the phone, yes, you need a phone or video call, emit the potential value proposition sentence exactly as you have written it, not a word different.
Do not do any extra run up other than hi, how much time do you have, pleased to meet you...
Then, shut up. This is called 'the golden silence' in sales. and write down exactly the first thing they say.
The first thing they say is the truth, and you need to listen to it.
after that, you can try to dive in, and they might say they didn't understand at first, but the reality is people like to please people, and all that subsequent talk is secondary. The first reaction is what you bank on.
When you are going to market, you will put ad money, web site visits, whatever, into a single sentence, and it must resonate. Period. And it must resonate with your target market - you did remember to define your target market and potentially do a value proposition for each. There are a lot of target markets who don't buy the product (investors, influencers), but usually you do that only after you believe you have a thesis and resonating message.