I really want to try something new but many of those shells are not POSIX compliant enough to be a daily driver and that's kind of a deal breaker. I often run external shell scripts to install various things and the fear that the new shell environment might muck up something I didn't notice is too real. Would have otherwsie moved to fish long ago, so for now it looks like zsh is as good as it gets (unless my concerns are unfounded of course).
I don't actually think it's that big of an issue. Most of those kinds of scripts should have something like `#!/bin/sh` already to ensure they can be run everywhere and you could always run a specific script in bash/zsh if needed.
Worst case, really, is that many of them do $PATH manipulation, set Env variables for you, or setup autocomplete and you'll need to redo that work in your shell of choice if it doesn't act like bash/zsh (e.g. I think nushell would be the most annoying in this way).
