Like the unsupported Zipster which works with bugs, it would be nice to have in-place use of zip files.
Ideally you could compress with the normal Finder function. It should get a special folder style icon with some kind of indication that it is really a compressed folder.
Dragging a file into the Zip Folder should “move” a file into the zip archive deleting the original once the file is moved in but if and only if that file is on the same volume as the Zip Folder. Moving a file from the Zip Folder out to a normal folder would copy the file out and if and only if the destination is the same volume, delete the file from within the Zip Folder.
It would seem that Total Finder would be the perfect place to implement this although Zipster did it without disabling SIP … albeit with a couple of annoying operational bugs.