I looked a bit into the JavaScript loaded when going to GitHub and my best guess as to what it’s using react for is the copilot chat.
It’s still using turbo rails and doing full ssr reloads. Something very at odds with react router which it’s also loading.
It’s still loading catalyst (their homebrew web component lib) which from what I understand doesn’t seem to offer react bindings. It even loads lit (another web component lib), which I couldn’t find the react bindings for.
If it’s just for the copilot chat I’d still say GitHub is mainly rails based though would love to hear if anyone has any more / better insight.
That said, most (not all) of it still works with Javascript disabled