Update to 5.5.1, it supports everything you would want.
Since you've mentioned that you thought loadiine didn't support it here's a list... quite a bit has happened...
- An exploit for DS games has been found called haxchi, this allows offline launching of any .elf file by replacing the content for the game, this shows on the home menu!
- It's possible to install games to internal memory OR a USB drive and they will show and launch exactly as if it were a eShop download with online functionality included... this needs nothing more than the homebrew with an app called wup installer y mod to install the game
- 1:1 disc dumping has become a thing, you can extract game files to install with the above bullet point using wud2app paired with wudump
- It's now possible to remove signature checks to install things like a homebrew launcher channel on the home menu... removing the checks are temporary though and needs to be done each boot
- There is a thing called coldboothax which will cause the Wii U to automatically launch the exploited DS game and will remove the signature checks automatically on every boot (kind of like Luma3DS but without A9LH)
coldboothax is very risky in its current state, if you accidentally move or delete the exploited game, or update the system to a non-exploitable version with it installed your Wii U will no longer boot
I think that covers most of the developments since the guide you've found...