Ask HN: Where is everyone finding interview partners for idea validation?

The common advice is to talk to a lot of people to understand pain points and validate your idea as much as possible.

In B2B it's not always that easy to find the right people. Sure, cold calling/emailing works to a certain extend but is more or less a pure numbers game.

Is there something like a linkedin but for people who are willing to talk about their work, challenges, ...?

Alternatively, do you have any hacks how to find such people on linkedin?