CDG to Gare Lyon connection

Two hours is cutting it close. The usual recommendation is four hours. You could make the train if all goes well, especially if you are in the front of the plane and have no checked luggage, but I would not be surprised if you missed it. Customs typically takes no time at CDG but I assume you will have to go through passport control. I usually fly business class to Paris and allot 45 minutes for deplaning, passport control, and collecting checked baggage but it has taken as long as 90 minutes mainly because of a wait for the luggage. The wait for a taxi is usually less than five minutes. The drive to Gare de Lyon without traffic is about 35 minutes. I have no idea if May 1 being a holiday will be a positive or a negative factor for wait time for the taxi or driving time for this connection.

There is typically little traffic at that time of the day, but regardless I fully agree that 2 hours and 12 minutes cuts it way too close... Allow 3h30 as a minimum, 4h being safer.

On a random Thursday in May, I found trains leaving the CDG train station going directly to Marseille at 2:57 and 5:06.

I made a 1:30 connection from plane to train a few weeks ago with about 30 minutes to spare. But, 1, there were fewer tourists in March than May, 2, I was in the front of the plane, 3, I went through an automatic passport booth for EU passports.

However, you only have to go through passport, pick up luggage if you checked it, and walk to the station. I think you can make the 2:57 ( must be onboard by 2:55).