Over the last couple months I turned a hobby into an app with a lot of Claude and Codex. I'm a video game collector so I know the pain of selling on eBay. There are a number of "buy lists" for many games. I wrote an app that let's you take a picture, identifies the games (does it well), and then gives you price comparisons between all the big buylists. The data backing it was a nightmare since it's a mix of google docs, word docs, json, html etc.
I also completed the iOS and Android apps and have them both in the store. Right now I'm struggling with the "I have an app, now what" phase. I would love any advice! I'm going to try reddit ads for r/flipping and a few other subreddits.