I did some of my own testing using plain old C (GCC) to get more insight. * Windows 10 console really likes UTF-16 encoded text. It simply cannot get UTF-8 input. * Forcing a program to get UTF-8 input **[ _setmode(_fileno(stdin), _O_U8TEXT) ]** combined with UTF-8 code page results in NUL characters, as is also the case with Nim. * Enabling the experimental UTF-8 support in **Regional Settings - > Advanced** does not help. * On the other hand UTF-16 input and UTF-8 output can be enabled without touching the code page, but then strings would really be UTF-16 encoded.
If only Nim would be more like Go on this matter.
