Generally it just means a collection of tools, patterns, ways of working, optimizations, testing systems, etc. I’ve been writing software professionally for 20ish years and the value of building a software factory almost always is only realized by the enterprise. Mainly because you also need enough smart engineers to upgrade and adapt the factory to the ever-improving and shifting software landscape and ecosystem and evolving business goals. I can’t imagine anyone who would have enough free time to build a software factory for hobby projects, except for those who hobby projects are their actual job, e.g. full time open source developers.