“places like GitHub that’s not fully open source (where you see all of the underlying source code).”
I’m a simple user of GitHub for source code. I decide what’s up there in my account (which is all of it). What do you mean by “where you see all of the source code”. Doesn’t each user decide that?
When I've looked up libraries in GitHub in the past (after finding others talk about libraries from blogs and such), I could either download the compiled code or download the source code. Say, if it was in C#, some sources had only the .dll libraries that I could download and reference in my code but never see the source code. But some sources had the source code in C# or VB that I could also download and put into my project(s), but I'd unlike the .dll's I could see the source code myself.
It's been maybe 8 or so years since I've used GitHub (the team I'm in now buys 3rd party libraries so I get our "shared" code from those vendors directly). But that's my experience.