While GitHub provides a … menu that offers Download (raw file content) and Copy Permalink choices, the Permalink shows the content in the GitHub UI, and while it has a viewer for formats like PDF, it only displays a couple of pages at a time and doesn't provide content seach.
The Download menu item results in a a Save As… dialog, and doesn't expose the download URL, which makes it very difficult to share a link to the raw content.
The URL of the raw content of a file in a Github repository can be determined using the Inspect/Debug features of a browser, and inspecting the actual HTTP requests and responses being generated when pressing "Download …".