[NTG-context] Extract bib entries used in a document

I was wondering if there is a way to get the internal bibliography manager to write out a .bib (or XML or Lua table) containing only the entries used in a document? Somewhat similar to BibTeX (https://tex.stackexchange.com/questions/41821/creating-bib-file-containing-o...). I guess it must be internally created, but I don't see, at least from the manual, a command like \exportbtxdataset[default][way=bytext][used_references.bib]. Two use cases: (1) Sharing a clean bib file with someone. (2) Merging bib files from different sources based on the document. (Or even by chapter.) Thanks for your reply. Benjamin