Reddit mentions of The Mom Test: How to talk to customers & learn if your business is a good idea when everyone is lying to you

You need to do customer development, check out books like "The Mom Test" and "Lean Customer Development". But before your prospective customers will want to talk to you you need to get some credibility. Try to create some content that solves problems that they are aware of, then you'll be able to talk with them.

I prefer customer interviews, e.g. The mom test (not affiliated) https://www.amazon.com/dp/B01H4G2J1U - you'll be able to capture potential problems that surveys will not.

I have also used Mechanical Turk on a few times but it was mostly a waste (for trying to validate product idea / improve onboarding / identifying new customer segments).

The Mom Test is quite succinct and makes some excellent points about what questions to ask and why https://www.amazon.co.uk/dp/B01H4G2J1U/ref=cm_sw_r_cp_apa_Io.jzbVEPG44Z

You can use Facebook Groups or an appropriate subreddit.

But before you start interviewing, I recommend you read The Mom Test: https://www.amazon.com/dp/B01H4G2J1U/ref=pe_385040_118058080_TE_M1DP

It's a great read that will help you ask the right questions. Hope this helps.