I would like to know - are there ways to access android resources and/or assets files (or files from any other folder) outside of an Activity (without passing context
If the folders are included in the Project Build Path, you can use ClassLoader access files under them outside the android.content.Context, for instance, from a POJO (in case if you don't want to pass a reference of android.content.Context):
String file = "res/raw/test.txt";
InputStream in = this.getClass().getClassLoader().getResourceAsStream(file);
To add folders into Project Build Path, right click your project -- Build Path -- Configure Build Path, add your folder (for example, assets if using later SDK version) as a Source folder in build path.
Check out the similar question I answered before at here.