Trying to transfer all data from one USB to another but can't even boot into Old USB

Hello,

I've been trying to do this for a while and can't seem to figure it out. I have a 32 GB bootable drive with Kali Linux on it. I ran out of space and want to transfer all of the data on it to a bigger usb that has 128 GB. Unfortunately, I can't even boot into my old USB. I plug it into my mac and when I try to power it on, it doesn't even see it, I just boot into macOS. On my bigger flash drive, I have Kali on it so if I need to do anything in there, I'm ready. I have exactly 881.8 MB left on my old drive. I was thinking that I messed up the grub boot loader somehow but when accessed the drive with an application called extFS for Mac, I see the configuration file and other things as shown in one of the screenshots. I also thought that I might've consumed up too much space for it to boot up. I don't know what to delete without breaking the Operating System though. I ran a command in the Terminal that told me how much space was being consumed by all files on the disk. The command was du -m | sort -r -n > disk-usage.txt. I can't attach the file that contains the result because it's too big to post. But I have attached a few screenshots of it. From the screenshot, you see that the folder usr is taking up about 13 GB of space. The rest of the items that weren't included only took up a few megabytes. The numbers on the left mean how much space a file is taking in Megabytes. There were some areas where the command couldn't access. I will attach that below too. Other than that, I have no idea what to do. Any help would be greatly appreciated.