@dalias @kkarhan @signalapp @monocles @lauren
Users, to a large degree, download the Signal app from the Google Play Store and Apple App Store. The apps shipped through this can hardly be verified by endusers. A modified version of the app could be delivered to selected users.
The official Signal app for Android is not fully open source and in its non-free parts does have a mechanism built-in that allows the code to be changed at runtime without allowing external auditors to review it.