For layouts and opening docs from other suites, it seems they rely on OnlyOffice, as listed on the marketing page of their Google Drive equivalent [1]. OpenDesk from ZenDiS (German counterpart to this project, also collaborating on La Suite) seems to rely on Nextcloud and Collabora Online for that [2]. Collabora and OnlyOffice are also present in Lasuite Drive's development environment [3].

Docs and Drive aren't the only products in this suite: they also provide alternative for Meet, Chat, GMail or Sheets. I have no doubt that Microsoft and Google products offer more features but my point still stands: a lot of employees (like myself) need productivity tools but only need the core features.

[1] https://lasuite.numerique.gouv.fr/produits/fichiers

[2] https://en.wikipedia.org/wiki/OpenDesk

[3] https://github.com/suitenumerique/drive/blob/46c9730d1b6d5c4...