No one can say the demographic number of ethnic groups in France....because they choose a number of years ago to make it illegal to collect such data (I know....they are that stupid).
Based on various foundations and simple “guesses”...somewhere around five to seven percent of the population are black African in origin or 1.3 million. The North African group (the Maghreb group) are estimated to be around 3.5 million. Note, this is info from 2008...and could be way off by today’s standards.
However, if you use original generation (first generation) immigrants...the sub-Sahara group is at the same level as Algeria (this leads back to the 1960s and the failed migrant programs of that era).