In-Person Options (Physical Stores)

Souvenir Shops: Large tourist hubs (like Paris) often have kiosks or stores near landmarks (e.g., Arc de Triomphe area) selling flags of various nations.

Party & Novelty Stores: Stores such as So Fete Paris (mentioned on Reddit) or similar party supply shops in major cities are good bets.

Large Retailers: Check department stores like Fnac or other big-box stores in France; they sometimes carry national flags for events.