The Nintendo Switch version is a marvel of porting. While the hardware is less powerful than a PS4 or PC, the dark, murky art style of Little Nightmares masks many graphical compromises.
Here's some general information:
As of the latest Switch firmware (18.0.0+), standard installers like DBI, Tinfoil, or Awoo Installer handle the "D" partitioning automatically. Manual D installs are largely obsolete for modern CFW users. little nightmares complete edition switch nsp d install