I'm also curious if its possible to make a custom library for Roku as I'm looking into possible ways to fix this particular issue.
In my case, we have an SDK, which composed of about 50 files all flattened onto 1 file on release, to give to our clients. Our clients wants us to use our SDK on a single Scene Graph Task node and this is where we're having some issues on the development stage.
Due to how the file imports work on Scene graph, either I have to explicitly import all 50 files or import 1 flattened release file for the task node to work, both are inefficient approach as I have to juggle between dev and release builds to debug my changes. The idea for the custom library was for the task node to only import 1 file that only contains the line "Library OurSDK" in it, making it so to dynamically load the SDK without explicitly stating the filepath