Struggling with Product Market Fit analysis for our startup

https://startupschool.org has some videos on the subject and more.

Basically, it all points back to your concept. Have you identified your bridgehead target group? The target group that is willing to pay ten times as much for your service as their current best alternative? If you cannot describe them, then there is a real risk that you are not on the right track. You then have to ask yourself: Why can I not do so? Is it because they do not exist, or is it because we have the wrong approach with your current concept.