I am wondering if the name of the repository is correct. I think it is fine to extend ets-gpkg12 as this test suite also tests GeoPackage 1.1 and 1.0, but it is confusing. Maybe it should be ets-gpkg11-nsg or ets-gpkg-nsg21 to avoid the version of the underlying specification?
From https://github.com/opengeospatial/ets-gpkg12-nsg/issues/1#issuecomment-361596523: