NGA has a difficult job when it comes to GeoPackage. They need to figure out the right way to distribute large amounts of geospatial data to users all over the globe. I know I am biased but I think GeoPackage is the right format for much of that distribution. Arcane formats like VPF, RPF, and NITF are a pain to work with. GeoTIFF isn't so bad, but it is a bit of a dated format and its compression capabilities leave a lot to be desired. (Because of this we see a lot of proprietary compressed formats in the field and that is even worse.)
The process is complicated by NGA's domain-specific rules. The approaches that most people use for their GeoPackages won't work for them. Among other things, Web Mercator doesn't work for them. The key step for them is to produce a profile that describes the rules for a compliant National System for GEOINT (NSG) GeoPackage. This process is underway and the goal is to produce the NSG Profile. They hope to be finished in the next few months.
From the GeoPackage side of things, I am excited about the NSG Profile. If NGA is able to distribute data as GeoPackage, I think it will make a big difference in long-term adoption. In addition, the NSG Profile touches parts of the specification (particularly extensions) that have not been examined closely to this point. It would be good to get some guidance on best practices for using them. Bring it on!