Is it a right to End-to-end encryption or a right to "encryption from everyone except government" ?
Legislation to the right to encryption would then just follow from it, but having it in the constitution would make it harder for future governments to pass certain kinds of legislation, or if they pass them, the supreme court would declare them inconstitutional.
They don't have the necessary majority to make constitutional changes without the CDU, I think. And the CDU is why we can't have nice things.
This should be the goal. In the days of the internet, mass surveillance, nearly eradicated privacy we need a right to have and use strong encryption without any backdoors.