This github/side project thing is at the far end of diminishing marginal returns. It of course wouldn't hurt but most people I've met at these companies (where I also worked for a while) do not have side projects or public code.

So if your goal is to get the interview, go through referrals. Don't expect anything from side projects.

Oh, you don't have to have side projects. But if you are struggling to get noticed, it can help.