Low level code is assembly, your code speak directly to the chip. best performance but can be tedious and more difficult.
Mid level is c/c++ as they need to be compiled with a compiler that will convert the code to the target architecture
High level / interpreter language are like python, lua, love potion and don't need to be compile but have a lesser performance.
Best is to use c/c++, there are a lot of libraries that have been ported to the switch.
You can of course use python and other interpreter language depending on what your application is.