There are big wishes for Signal to adopt the perfectly working Flatpak.
This will make Signal show up in the verified subsection of Flathub, it will improve trust, allow a central place for bug reports and support and ease maintenance.
Flatpak works on pretty much all Distros, including the ones covered by their current “Linux = Ubuntu” .deb repo.
To make a good decision, we need to have some statistics about who uses which package.
Your data is always encrypted before it reaches the AWS servers though, so it’s not like Amazon has access to them. The phone number/nicknames is still in progress, but it’s hard to do that securely, and given that their user base is really big now, they also need to make sure it works well for everybody.
The concerns about AWS servers are around metadata. If metadata were not a concern, why not just use Whatsapp? They use the Signal protocol so messages are end-to-end encrypted by default, and most people already have it or are willing to download it as compared to Signal.
Signal also encrypts your metadata. (And notably, WhatsApp does not.)