I haven’t bothered with any sort of NUS downloader in years because converting the content has always been a pain in the ass. In the past couple years there’s been multiple WiiU rom collections uploaded to archive.org . Just recently, I set up my WiiU with a 4TB hard drive and used JDownloader to pull the entire North American WiiU library in USB installer format over the course of a couple days. Installing everything was a bit of a chore, but at least I didn’t need to deal with any conversion on the PC side.