French authorities declare the use of Microsoft Office and Google Docs illegal in schools and education markets, as they don’t follow GDPR and might disturb later competition by making students used to these proprietary solutions.

https://questions.assemblee-nationale.fr/q16/16-971QE.htm

Looks like it only applies to Office365 online and Google docs, not the installed MS Office suite. The fact that these companies are US based means there is no guarantee that student’s data isn’t accessed by the US government, which seems to be the main issue.
@thelinuxEXP This is when OpenOffice or Collabora could fill a need. But would require the school system to create the host.