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.
There is Flare. I haven’t used it myself because it’s not official and I don’t know what it will do to e.g. my backups, but just sharing in case you’re interested.