I have my own remotes with my own CI and it’s all ultrafast because I can just make assumptions about the way I write software.
None of these platforms are necessary for development. Just take from them what you want and build your own universe. This grade of CRUD software is generally solved.
There are places you need other people. Stuff like ffmpeg or GPU kernels. But other kinds of code is kind of unimportant. Not being part of this community loses you nothing.