Switch hackers Yellows8 and Plutoo have released libnx, a C library to write usermode homebrew for the Nintendo Switch.
Of course, writing and running Nintendo Switch Homebrew will require access to a native Nintendo Switch exploit, which does not publicly exist yet. Pegaswitch is “only” a Webkit entry point which does not give native access to homebrew at the moment.
However, Multiple hackers have confirmed that Nintendo Switch on firmware 3.0.0 and below are vulnerable to smhax. Smhax is an undisclosed native exploit for the Switch, but some people are assuming that the release of libnx implies smhax, or some other native exploit, will be released soon.
Libnx is based on libctru, the library for native 3DS homebrews.
For now, libnx looks extremely barebones. In particular there are no meaningful homebrew samples included yet, although I assume these will come soon if an exploit is released and the scene gets excited about Switch homebrew.