I will not promote... Built a serious prototype from a client pain point and now I am unsure if I should partner or launch solo

I’ve spent the last six months building a niche software platform for a sports event operations use case. This started from conversations with someone I’ve known for years through my gym community. He is a gym owner with valuable connections in the space. The original idea came from his pain points and what he would want as a user... but the actual product is not some totally original concept. Similar products already exist in the market. I designed and built the prototype completely myself, kept improving