Considering that you are a developer, I would first of all make an estimate of how much work it would need to create an MVP - meaning minimal useful features, b

Considering that you are a developer, I would first of all make an estimate of how much work it would need to create an MVP - meaning minimal useful features, but polished. Then I would try to understand how long it would take to create that MVP in your free time - realistically. Then I would double the estimated time, and decide if I'm comfortable with the idea of working very very hard for that long before getting any tangible result. If the answer is yes, I would try the solo/MVP way. Otherwise, I would try to create a good presentation and see how relevant people (possible customers + possible investors) react to it.