This might be part of your struggle, perhaps, as those kinds of things ("product did x y and z, I wrote it by myself, it's still in use", etc.) fall into the "s

This might be part of your struggle, perhaps, as those kinds of things ("product did x y and z, I wrote it by myself, it's still in use", etc.) fall into the "solved a problem" category (valuable, don't get me wrong) rather than the "built a clean, maintainable system" category ("100% test coverage, followed sem ver and git flow, maintained a 7+ on pylint, used these design patterns", etc.). Folks in the latter category don't need 6 months for any Python-based system. Folks in the former category are useful in certain ways, but difficult to plug into a larger team, and if companies know enough to know they need a "Python" developer, that's because someone technical already picked Python, and the position is to work with at least that one other technical person. It's likely similar with JS, Ruby, and other "newer" languages that have reputations for being "easy to pick up".