I think we're using different definitions of "control fully." In my view, in order to control the encryption process fully, you must control the device doing the encryption. If you're using an OS with a keylogger, you DON'T have "end-to-end encryption that you control fully" because you don't control one of the ends.

If you fully controlled both ends, the security of the wire would be irrelevant. It could send copies of every message you send straight to your enemy's inbox and it would still be secure, because only the two fully controlled ends could decrypt the messages they send one another.

If you don't control the device, you don't control the encryption.