How do I create customer pools for ideas/concepts

I joined Product Hunt yesterday and it looks like a wonderful community of innovators, creators and marketeers. I spent the last year building a small community of founders and mentors to help founders launch their startup to customers not investors. I'm in the process of putting together a narrow set of idea validation tools to help founders find out early if there is a level of customer need for their idea. Personally I think surveys are very weak strength validation as generally people lie and just want to complete the questions ASAP. I know there are exceptions and don't really want to get into discussion about surveys in this post. My biggest challenge is to find different customer profiles to target the validation experiment to. I know this can be done with paid Facebook, Google Ads, etc but I'm looking to explore other ways. I thought Product Hunt might be a source of users for targeting but can't quite get my head around how I would use the site to build a database of people interested in ideas/concepts. I'm not trying to build another Product Hunt but something in the same domain. Please could you help steer me to posts on this discussion board or advise me. From what I've seen, this is the right audience to ask.