If I use fish, I want to make use of it, and that means I will want to convert scripts, or simply learn to write scripts compatible with fish.
Shell scripts from third parties stick with whatever shell they were written for (ie. /bin/sh or /usr/bin/env bash), and commands copy/pasted from the internet are either quickly executed with bash (one-off) or ported over. Because I like to have such in my history (fish is configured to use atuin), I want to keep using the same shell, so I try to stick with fish. If I cannot convert a command (usually a bunch of commands) to fish, it is PEBCAK and a learning curve/experience.
As for tmux, that is solid advice, because it also allows to stick with a shell which is known to work. I've come to like zellij with alacritty, with zellij the option is default_shell. But now that I use ghostty, I don't use a terminal multiplexer locally any more; only remotely. And there I still use tmux.
Shell scripts from third parties stick with whatever shell they were written for (ie. /bin/sh or /usr/bin/env bash), and commands copy/pasted from the internet are either quickly executed with bash (one-off) or ported over. Because I like to have such in my history (fish is configured to use atuin), I want to keep using the same shell, so I try to stick with fish. If I cannot convert a command (usually a bunch of commands) to fish, it is PEBCAK and a learning curve/experience.
As for tmux, that is solid advice, because it also allows to stick with a shell which is known to work. I've come to like zellij with alacritty, with zellij the option is default_shell. But now that I use ghostty, I don't use a terminal multiplexer locally any more; only remotely. And there I still use tmux.