Disappointing to see nothing on Signal's blog as to the mass outage due to their dependence on AWS. Solely very specific social accounts. Their AWS use for serverside has not been a secret, but it would be good to have a detailed, transparent description of how far this relationship goes, if they have plans to add more resilience, decentering.
Their server side code is OSS yes, but just for audit purposes. To use it you'd need to rebuild the client apps, pointed to your instance.