You have an idea. You are not sure it is worth it yet.
A market you know. A problem you have seen. Maybe a few competitors in mind. But you do not know whether it is worth building on.
This is where we work before writing code or opening Illustrator. Idea audit, market analysis, possible business models. Not to make you feel good: to see if there is something real worth investing time and money in.
If it does not hold up, better to know now.