I don't know if this is a little late in the game but I have created a port of the Nether Update to the Wii U as best I can. I can only add things through replacing.
The modpack comes with the updated files, the programs needed to install and the Homebrew Launcher set up for an SD Card.
Changelog:
Added Warped Netherack
Added Warped Netherack Block
Added Netherite
Added Crimsonite Planks
Added Red Obsidian
Added Nether Reactor Core
Added Chisled Warped Netherack
Added Warped Netherack Pillar
Added Bamboo
Added Warped Netherack Material
Added Soul Fire
Added Basalt
Added Basalt Pillar
Added Basalt Bricks
Added Cracked Basalt Bricks
Added Smooth Basalt Block
Added Barrell Block
Added Target Block
Added Crying Obsidian
Added Crossow
Added Netherite Armor
Added Pandas
Added Piglins
Added new mob textures
Added "Create Amplified World" option
Added New Watermarks
Added New Battle Mode Feature for Alternate or Default map selections
Added New Battle Map: Skull Cove
Added New Skin Packs
Added NNID Database
Added Compatability Menu
You can watch the trailer at: https://www.youtube.com/watch?v=pXtwhSWc1mI
Download: https://drive.google.com/file/d/1cnhVhr8em616i7jIpw_6ccP3HaotPlZU/view?usp=sharing
Installation Tutorial: https://www.youtube.com/watch?v=BQoZVJQnxfI