This may actually be simpler than you think: A) Identify your users, who they are? B) Find active niche places where they are in high density. These could be

This may actually be simpler than you think: A) Identify your users, who they are? B) Find active niche places where they are in high density. These could be specific people on LN you can find searching by role/position, topic-oriented FB groups, industry-specific conferences and events. C) Share your product hypothesis and ask for their feedback. Specifically, do not expect a spot-on feedback from people who are not in your target group - indiehackers or HN are nice places full of great people, but are they really your potential clients? Or should you rather look elsewhere.