Folks here may be interested in the latest release of Moonshine, 2.0.0.
Moonshine can help with finding sample file formats if you know the first four bytes of the file type that you're looking for.
It dawned on me that perhaps only a few people know about the tool and the UK Web Archive interface that it leverages. I've written some more about it here:
Moonshine 2.0.0 comes with a new sampling mode to retrieve samples of potential matches to your format type from across all the results available in the UK Web Archive. This should help with signature development workflows and increasing your confidence in the signatures that you're creating.
Give it a try and let me know how it goes! Let me know via GitHub if you have any suggested improvements or find and bugs or issues.