ok it looks like this

 exec tail -n +3 $0
 menuentry "Debian" --class fedora --class gnu-linux --class gnu --class os {
        set iso_path="/home/bruh/Downloads/debian-live-13.0.0-amd64-cinnamon.iso"
        export iso_path
        search --set=root --file $iso_path
        loopback loop (hd0,2)/$iso_path
        probe --set isolabel --label (loop)
        linux (loop)/isolinux/vmlinuz root=live:CDLABEL=${isolabel} rd.live.image verbose iso-scan/filename=${iso_path}
        initrd (loop)/isolinux/initrd.img