I'm not terribly familiar with French politics. France does have other significant left wing parties, but they (presently) hold fewer seats and are less hard left.

https://en.wikipedia.org/wiki/List_of_political_parties_in_France

https://en.wikipedia.org/wiki/Socialist_Party_(France)

The Socialist Party (French: Parti socialiste [paʁti sɔsjalist], PS[a]) is a centre-left[2][3][4] to left-wing[5][6][7][8] political party in France. It holds social democratic[9] and pro-European views.[10][11] The PS was for decades the largest party of the "French Left" and used to be one of the two major political parties under the Fifth Republic, along with the Rally for the Republic in the late 20th century, and with the Union for a Popular Movement in the early 2000s. It is currently led by First Secretary Olivier Faure. The PS is a member of the Party of European Socialists, Progressive Alliance and Socialist International.

https://en.wikipedia.org/wiki/The_Ecologists

The Ecologists – Europe Ecology The Greens (French: Les Écologistes – Europe Écologie Les Verts), commonly known as The Ecologists (French: Les Écologistes, LÉ) and formerly as **Europe Ecology The Greens[**2] (French: Europe Écologie Les Verts [øʁɔp ekɔlɔʒi le vɛʁ], EELV [ə ɛl ve]) until 2023, is a centre-left[3][4] to left-wing[5][6] green[7] political party in France. The party is a member of the European Green Party.[8] It was formed on 13 November 2010 from the merger of The Greens and Europe Ecology.[9]