I am not aware of any commercial tools that can produce ECRG files. The specification looks to be well-specified, and it doesn't seem like an impossible format to create a writer for. The only producer of ECRG files I'm aware of is NGA and its affiliates, and I would hazard a guess that they don't rely on existing commercial tools for this task.
Note that the specification includes NITF 2.1 file frames (relevant GDAL documentation), XML table of contents, and Shapefiles for footprint information. You are in luck in the sense that GDAL supports writing all three of these formats natively, including the JPEG2000 compression required for ECRG. So, most of the work will be in conforming to the data specification. Provided that this is currently exclusively a military format, it's unlikely this format will be supported by the community without some leg-work.