I have modified pkg(8) to handle Zstandard-compressed packages. This functionality is not available on stock version of pkg (e.g. pkg used by FreeBSD Ports collection and DragonFly DPorts).
I've rebuilt the DragonFly repository and relocated it here:
When DragonFly 5.0 comes out (any day now), a new repository will be rebuilt and replace the 4.10 version (which is for the development branch).
New repositories for FreeBSD and Linux will soon and I'll post when that happens.