Ask HN: Where to find free/volunteer programming apprenticeship or mentoring?

I've done some online bootcamps, and made a few contributions to open source software projects. However, the quality of code on many of the projects I've contributed to is very sub par, and when I ask questions the developers they themselves don't always understand how to fix it and are of little to no help on continuing education. I also do not feel the coding practices are up to commercial grade.

Are there any semi-professional open source projects that would help with mentoring? I am primarily interested in Python, C, and C++, and Golang but always open to trying new things.