Why not look for a job with a established development team? I cannot imagine how anything could replace the experience you get from working directly with other developers. You will learn more than just technical skills. You'll learn more about how to predict time estimates, how to interact with other groups in the company, how to set up good infrastructure for development, deployment and support. If you learn all these things yourself, you will make lots of mistakes along the way which can harm your current employer.
There's great value in quality technical mentorship, but they're trading it off for an opportunity to learn leadership, autonomy, and cross-functional skills at a very fast pace... That's not a route for everyone but it could be a massive opportunity for the right person.
