FODG format is a special XML based drawing format based on OpenDocument schema and thus used in OpenOffice/LibreOffice and similar productivity suites as one of the default drawing format.
If you got files in this format and want to turn them into standard graphics files (which is pretty much what fodg to jpeg conversion represents), just download the suites and use the Draw app to resave your drawings to whatever format you need / is possible.
Updated: August 16, 2023