>    data.encode('utf-8', 'replace').decode('utf-8')
>    data.encode('utf-8', 'ignore').decode('utf-8')

Why not the reverse:

os.fsencode(data).decode('utf-8', 'replace')
os.fsencode(data).decode('utf-8', 'ignore')

Note that "backslashreplace" needs to be enhanced to work when decoding too.
Note that "xmlcharrefreplace" doesn't make sense here: it encodes a *character* reference, but you're precisely trying to represent something which fails interpreting as a character.

(AFAIK, XML can't represent non-text data, except in NDATA sequences)