The Verdict: Need More Info
The route exists, but its clock starts on your wedding day: four or five years of marriage. Plan the wedding so that it can be transcribed into French civil records.
Article 21-2 sets four years, or five if you have not lived in France three years in a row since the wedding and your spouse was not on the consular register while you lived abroad.
If you marry outside France, the marriage must be transcribed into French civil records before you can claim, and it is easier to arrange with the consulate before or soon after the wedding. Abroad, make sure your partner is registered with the consulate, which keeps the four-year rule open.
You will also need French at B2, so if you are starting from a low level, the years of waiting are the time to learn.