Does F-Droid support signed releases, and does Signal sign their APKs? In fact, aren't all APKs signed?
Some forks of Signal are, though[2].
[1] https://community.signalusers.org/t/how-to-get-signal-apks-o... [2] https://forum.f-droid.org/t/signal-in-f-droid-in-2018/2847