You will go through Passport control / Immigration at CDG and collect your bags / do Customs at MRS.

That may cut it close. IF your flight arrives on time AND you are flying out of the same terminal, things still may be tight. Our experience, and that of two other family members on separate flights, last year with CDG Passport control was that they were very slow (verging on rudeness) in processing people. I would prefer a minimum two-hour window there. (If you have booked tickets on separate airlines, which can be risky, I would want even more time.)

Tight, I note you mention Paris airport. You do know there are three and you are aiming to stay in just one?

My son goes home to France frequently and almost always he reports that there are just a few Immigration desks open with long lines - this seems endemic.