im wondering how u can dllimport within oxide because u are encapsulated in a singular file
or how u can run custom assembly(but that requires virtualprotect which isnt allowed i tested it) or c++ code
i saw this https://umod.org/community/rust/15664-accessingreading-a-file-via-a-plugin thread and one guy replied with

Config.ReadObject<ConfigData>();
Interface.Oxide.DataFileSystem.ReadObject<>()​

The config library in Oxide only handles json files, but you can write an extension that uses multiple files else disable the sandbox for plugins to use other filesystem methods.

You can use other DLLs that would have to be manually referenced; which there are a few threads that discuss this. https://www.google.com/search?q=site%3Aumod.org+reference+dll