This is a great question because it is a real problem. However your constraints make it sound like an academic exercise as opposed to business problem. Especially this…Unfortunately, I’m unable to offer financial compensation to the interviewees. Each interview will be conducted via video call and is expected to last about 30 minutes.

I presume this is to ensure you are finding people with sufficient level of problem acknowledgment that they want to talk to you or it is code for you can’t afford it (no offense intended).

If you are able to spend money (not on compensation) you could try something like AYTM https://aytm.com/ and structure your survey to try and connect via email and go from there. If not this then you can literally pay people to find the sources for. Here in Australia it is about $150 per head, generally that is combined with $100 gift card. As you have stated the compensation bit is off the table.

If none of that is useful I think u/LongIslandIceTeas has some good ideas,

G’day - Great post and very timely for me. Thanks heaps!!! I really like how you put in “Here is how to get the conversations going”.