I'd try a modern file system with de-duplication/copy-on-write support. `cp` creates reflinks automatically if the file-system supports copy-on-write.

> Support for reflinks is indicated using the remap_file_range operation, which is currently (6.18) supported by bcachefs, Btrfs, CIFS, NFS 4.2, OCFS2, overlayfs, and XFS. Some external file systems support them too, including bcachefs and OpenZFS.

https://unix.stackexchange.com/questions/631237/in-linux-whi...