Nano Memory card does not show up in Finder nor Disk Utility
Working as designed.  macOS doesn't support the linux filesystems that linux uses to boot.  The one I use for booting is ext4.

check what filesystem you formatted flash driver with. 

For ext4, you can install one of these drivers. 

http://osxdaily.com/2014/03/20/mount-ext-linux-file-system-mac/

https://www.paragon-software.com/us/home/extfs-mac/#