The official "Wii U USB Helper" does not have a stable, native Android version . There was a mobile project called USB Helper GO
Warning: This workflow is tedious, error-prone, and only recommended for extreme enthusiasts. wii u usb helper android
Regarding legality, using the Wii U USB Helper for backups of personal data and for transferring legally obtained content is generally considered safe. However, users should be cautious about distributing or using copyrighted material without permission. The official "Wii U USB Helper" does not
The short answer is no—there is no official, fully functional Android port of Wii U USB Helper. However, the discussion surrounding such an app reveals much about the evolution of emulation, the technical hurdles of mobile platforms, and the legal gray areas of game preservation. Use: ZArchiver can unpack
This is the most functional "Android solution" for 99% of users.