After the Tchap project based on Matrix, the French Prime Minister asks anyone in the gouvernement to use Olvid, the only app validated by the ANSSI, with metadata encryption and no centralised architecture nor contacts discovery. But only the front-ends are open source, not the back-end.
For WhatsApp, sure. For Signal, no.
There is an argument to make about using custom versions of Signal that route their traffic through your own infrastructure.
This would count as France running their own service.
Given that Signal relies on centralized servers to route traffic, and if I’m not mistaken they use AWS in US instances, this means that your Signal traffic is being fed straight into the US security services’ infrastructure. France might be a staunch ally of the US, but they do go through great lengths to preserve their independence.
Sure, I’d be the last person to say that Signal is perfect and secure. But it’s a damn sight more secure than WhatsApp.