Godot does support consoles to some extent. The problem is that porting to a console is not trivial, demands time and testing. Worse of all, licensing for consoles requires an NDA, so it's not possible to disclose the source for those, Godot can only handle it to licensed developers. The devs would also need to own devkits for the consoles to keep testing, and those are not free (you usually can loan then for free, but for maintenance the devs would have to keep it for a longer time than a loan permits).
With those caveats, it's not worth for a FLOSS engine to keep maintaining code for consoles.
Now, if you want to make a port for Nintendo Switch yourself, I'm sure the devs can help you out and answer your questions if you ask in the IRC channel (#godotengine-devel at freenode).
You probably will want to wait for (or work alongside the current development of) the new renderer for 3.0 which will support OpenGL ES 3.0 with much more modern techniques than Godot 2.