I think you've missed the point there. I was demonstrating that there are multiple off-the-shelf filesystems available that Nintendo wouldn't need a license to use. I'd consider it very very very unlikely that Nintendo engineered their own filesystem for this - it's a massive undertaking that takes years of work. Much more likely they used an off-the-shelf OSS filesystem and made their own adaptations to it.
If you had read the blog post, that I linked to, you should know that Nintendo DOES NOT WANT GPL software anywhere. They blocked the developer for doing so. Nintendos rules are: do not use GPL software. Which means if the developer would have included the GPL license (and/or told Nintendo that they included GPL-licensed software), Nintendo wouldn't have allowed the game to be released.
Which means even if they changed the game release to be GPL compliant (and that was the goal for the ScummVM team), Nintendo wouldn't have allowed it anyway.
see
ScummVM blog said:
And it was really nice at first, but pretty soon the lawyers found that Nintendo explicitely prohibits use of open source software together with their Wii SDK, and as such it was a big fault from Atari side.
Which then resulted into this
ScummVM blog said:
Any copies beyond this period or any reprints get fined with quite high fine for each new/remaining copy. The remaining stock has to be destoryed.
btw. Wii had its own proprietary filesystem as well. Game consoles don't need all sorts of features. A pretty basic FAT-like filesystem is totally fine, which is trivial to do. Wii had something like that.
I'm betting the partition table will be completely non standard. If it were standard, you'd be able to split partition the drive and the Wii U wouldn't require the complete disk.
If the partition table wouldn't be standard, connecting such a harddrive to any PC would result in a "this drive seems to be unformatted/unpartitioned" / "this drive appears to be corrupted" error message. I doubt Nintendo would want that. Instead they will use another partition type for their partition. Which will result in any OS reporting it as "unknown/unsupported partition", which is perfectly fine.
You wouldn't be able to split the partition then, because partitioning software would notice that the partition type is unknown. It can't reduce the Wii U partition because of that.