Not on phones. You have 0 guarantee that the open source code is actually the code that runs on your device. And you have 0 guarantee that the device itself is

Not on phones. You have 0 guarantee that the open source code is actually the code that runs on your device. And you have 0 guarantee that the device itself is not compromised. And you have 0 guarantee that the OS is not storing your data. E2E on mobile devices is a security blanket with holes the size of the solar system.