Thanks for this honest post-mortem. It sure wasn't easy to describe your shortcomings in our world filled with infinite news of shiny web successes. I think one of the main takeaways can be that attacking a large project like this should not be done alone. It's a huge amount of tasks and context switches for one person to handle, and the risk of loosing motivation and even running into a burn out is much higher.

I think the way to go for solo devs is mobile (Android + iOS), since the project scope is often more limited / condensed and it's easier to get users with little marketing efforts.