This starts as a pet project which was an excuse to keep in touch, experiment with new technologies and most importantly have fun.
Given that, it sounds like you've already won, no matter what happens next.
As far as advice goes, I'll just leave a couple of book recommendations.
https://www.amazon.com/Discipline-Market-Leaders-Customers-D...
https://www.amazon.com/Differentiate-Die-Survival-Killer-Com...
https://www.amazon.com/Positioning-Battle-Your-Al-Ries/dp/00...
https://www.amazon.com/Its-that-Small-Fast-Slow/dp/006662053...