> Maybe the internal FB Messenger app has a slide button to switch to the backup network for those in need.
Having worked for 2 FAANG companies, I can tell you most core services like which FB Messenger would be using internal database services and relying on those which would be ineffective in a case like this as it would not work and the engineering cost to design them to support an external database would be a lot more than just paying for like 5 different external backup products for your SRE team.
Having worked for 2 FAANG companies, I can tell you most core services like which FB Messenger would be using internal database services and relying on those which would be ineffective in a case like this as it would not work and the engineering cost to design them to support an external database would be a lot more than just paying for like 5 different external backup products for your SRE team.