Will a Mac boot with Clonezilla?
Yes, it's doable!

Testing on a MacBook Pro (Retina, 15-inch, Early 2013), as it's the oldest Mac I have access to today…

I went to https://clonezilla.org/downloads.php and clicked on alternative stable - 20200428-focal, then in the next window left 1, 2, 3 as set and clicked the DOWNLOAD button.

While the zip archive was downloading I prepared the USB drive in Disk Utility so it's a single FAT32 partition with an Master Boot Record. The output below from Terminal shows how it should look, although the disk number may vary on your system:

$ diskutil list disk3
/dev/disk3 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *8.0 GB     disk3
   1:                 DOS_FAT_32 UNTITLED                8.0 GB     disk3s1
$ 


Unzip the downloaded zip archive to the root of the USB drive while maintaining the hierarchical directory structure contained within the zip archive, as shown in Terminal using ls -al:

$ ls -al
total 128
drwxrwxrwx@ 1 me   staff   4096 May 31 07:22 .
drwxr-xr-x@ 4 root  wheel    136 May 31 07:02 ..
drwxrwxrwx  1 me   staff   4096 May 31 07:22 .disk
-rwxrwxrwx  1 me   staff    188 Apr 28 22:56 Clonezilla-Live-Version
drwxrwxrwx  1 me   staff   4096 May 31 07:22 EFI
-rwxrwxrwx  1 me   staff  18092 Aug 11  2015 GPL
drwxrwxrwx  1 me   staff   4096 May 31 07:22 boot
drwxrwxrwx  1 me   staff   4096 May 31 07:20 home
drwxrwxrwx  1 me   staff   4096 May 31 07:22 live
drwxrwxrwx  1 me   staff   4096 May 31 07:22 syslinux
drwxrwxrwx  1 me   staff   4096 May 31 07:20 utils
$ 


Then booted the Mac with Clonezilla Live on USB by pressing the Option key at startup, selecting EFI Boot and pressed Enter.



However …

That all said, while it is possible to boot a Mac with Clonezilla Live on USB; nonetheless, I would just use Disk Utility while booted from macOS Recovery from a macOS USB Installer, and use it to mirror the drives using the Restore button.