they can keep control of the app and change it freely without most people noticing, especially if a modified version is only pushed to certain individual devices.
Is it possible though? like Google Play updates the modified app only for certain individual devices
Is it possible though? like Google Play updates the modified app only for certain individual devices
Sure that is easily possible. They can also push an update to everyone and a slightly modified version the same time only to certain devices.
In fact if this is still true then Google could even dynamically push a exploit into Signal without an update to the app itself.