However, France is also subject to the European Arrest Warrant, which means they are "precluded from refusing the surrender of their own nationals wanted for the purposes of prosecution, but they may condition the surrender of a requested person on his or her being returned to the issuing state to serve any sentence ultimately imposed". This is obviously only for other European countries, but I bet you could then extradite from such a country to extra-EU jurisdictions simply with political help.

So let's say person X is wanted in the US. They get Country A to emit a warrant for them, A gets X from France, then extradites X to the US.