Have just come back from France, a few days in Paris and some time in the Champagne region. All very quiet and relaxed and so easy! You need to show that you’ve tested in the last 48hrs or double jabbed at restaurants etc, but no issues at all we just uploaded our nhs vaccine certificates onto the French Covid app. There were literally testing tents all up the Champ-Elysees. It was so quiet and felt much safer than Cornwall did a couple of months ago!
You also have little testing tents everywhere in the rest of Paris, next to each pharmacy they belong.
As for the test, it's less than 24h now (if you are not fully vaccinated or for non vaccinated kids of 12 +).
I traveled back to Paris from Spain yesterday but we had a (very nice) day stop in Geneva, Switzerland is not in the EU but is in the Schengen space so there were just Covid control by the airline before when checking the boarding pass and identity cards, nothing at the arrival.
When we took the flight to Paris in the evening, the airline also checked briefly and that was it.