Currently, the existing XCI/NSP tools either need a PC or can only do one or the other, but now scene developer @HiD has released the first version of dOPUS and it can manage both NSP/XCI installs directly on your Switch console itself. You can grab it here!
Keep in mind this is a first alpha release. If people like it and use it, I might add more features!
As always I'm not responsible for any damage caused to your switch or your data.