It seems like there are two decent community built options:
https://software.opensuse.org/download.html?project=network:im:signal&package=signal-desktop
And
I’ve been using the flatpak so far, but according to discussions I’ve found about the rpm package, “it builds signal and its dependencies offline and without pre-built binaries shipped along with the repo” (Packages for rpm-based linux distributions · Issue #1630 · signalapp/Signal-Desktop · GitHub) which sounds very good for security. Any thoughts?