Comment by stonogo

For those following along at home, "golang.org/x/pkgsite" redirects to "https://pkg.go.dev/golang.org/x/pkgsite", which declares the repository to be at "https://cs.opensource.google/go/x/pkgsite", which gives a "Permission denied" error page unless you fetch code from Google Tag Manager. So it's all nicely open source, and not proprietary, as long as you subject yourself to Google's tracking mechanisms, or sign into your Google account, and do not license any libraries public domain -- Google will use them, but not show them to you. So as you can see, there's nothing to complain about, and we should all thank Google for their grandmotherly kindness.