I've been exploring opening #SolidProject files from desktop file manager/Android intents
There's a few tensions to resolve for RDF documents:

1) base uri is commonly inferred when documents are dereferenced, i.e. it's not in the document contents
2) the origin of a document may be ambiguous, particularly as Android makes it easy to share content and hard to access files
3) files with identical relative URL content can be different in absolute terms, so file deduplication needs to be RDF-aware