In most cases tar to dmg conversion is related to repacking of TAR archives to DMG, often to transfer archives between Unix and Mac computers. This works for common data, but of course not for app installers.
You should be able to repack the archives with tools, such as DropDMG, but you might as well achieve this manually by first decompressing the .tar files and making new DMG disk image from the data.
Updated: October 27, 2023