Honestly every arrondissement has some new food hall or covered market that looks authentic but charges €15 for average sandwiches. Marché saint-germain, marché saint-honoré, even parts of marché des enfants rouges in the marais now.

The real test is whether locals from république or belleville are eating there at lunch on weekdays. If its all tourists taking photos of their €12 burgers around châtelet then run away. Proper food halls have office workers grabbing quick meals for under €8 near métro stops.

Best actual food halls that locals use: marché couvert saint-didier in the 16th, marché saint-germain but only the small vendors not the trendy restaurants, parts of belleville covered market near métro. These places have real prices and real food not instagram nonsense for saint-germain tourists.