there seems to be much confusion
-- antigen tests -- yes you can get them in most pharmacies. You may need one before returning to your country.
BUT - i would be wary of having this done at the start of the trip as a way to get a 72 hour pass to use in restaruants/muesums etc. IF You test positive (even a false positive) then your trip is over, you must quarantine etc.
--QR codes/conversion/pass sanitaire
anecdotally "some" people have had luck. Do NOT rely on this . the same rumors were floating around when I was there in August. I contacted over 20 pharmacies (Paris, Nice, Antibes) and NONE would do it