Your screenshot shows that your original error message was in fact correct. For some strange reason the DLL that is needed for the python3.8 unicodedata module can not be found.
One thing you could try is to download and install Python 3.8.3 from
www.python.org and install it and then open a command prompt to fire up that just added version of Python 3.8.3 (not the one in the Sigil folder) and try the:
import unicodedata
test again and see if you get the same error message.