Is it possible to load non-packaged asset at runtime/on load in packaged game?

I’m trying to make a game which has extremely high accessibility mod-wise. Does Unreal support, in any way, loading non-packaged assets (like a .ogg, .obj or .txt) file in a packaged game? Or do all assets need to be specifically packaged?

For reference, the levels of modding I plan on allowing will be at LEAST like the 1999 game Re-Volt, if not more.

I mean. Worst to happen, I DID already plan on making in-game editors with pre-built parts, so I could probably write an importer or even provide that as a service to people, but it would be really cool if they could at least put the files in a folder according to a predefined format and either load it at run as a mod or have the game package it for them.