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.
Source: https://www.politico.eu/article/france-requires-ministers-to-swap-whatsapp-signal-for-french-alternatives/
When Real-Time Bidding allows foreign states and non-state actors to obtain compromising sensitive personal data about key European personnel and leaders to get location data, time-stamps, websites and apps activities; switching to a local messaging service appears to be a weak patch. You can get an overview of the actual situation here : https://www.iccl.ie/digital-data/europes-hidden-security-crisis/
It's not a patch. It's eliminating an attack vector, and the one which is more pervasive and easier to exploit.
Security-minded people pay far more attention to what software you run than what hardware you have.
You didn't read the article apparently.