Hey, We are working on supporting all shells in our v6 branch that you can track here: https://github.com/MisterTea/EternalTerminal/tree/v6 . We have thousands of users, so changing the protocol isn't something that we can do lightly, but we want to support fish and other shells, so we will definitely roll it out once it's ready.
But, it would be a shame if we can't get this into Debian main just because we only support bash/zsh. That doesn't seem like a good reason to block the package. Jason Gauci.