Train Copilot on external resources (URLs/PDFs) or share Fibi training data

I want to be able to train Copilot on external resources like URLs, sitemaps, and PDFs, or have it share the same training data pool as the Fibi chat agent. Currently, Copilot seems limited to native Featurebase content (Help Center, Macros, etc.), and I need it to draw from my external workspace content to provide better responses.