There are hopes, especially in the wake of system overloads and the recent floods demanding very good reach for evacuation orders (beyond what could ever be expected without cell broadcast), that Germany will move to cell broadcast as the medium for critical warning message distribution. It's the only one that has no sclability issues and reaches basically every mobile phone with reception.

The warning app had been dreamed up because it didn't require going to cellular network providers and demanding a way to trigger cell broadcasts. At worst, it's software-license-gated on the currently-deployed base stations.