I use zsh with some extra stuff, like the netmask zsh theme ⇗, the only perfect ohmyzsh theme.
However, for startup scripts, I use dash shell. Gentoo devs recommend —— citation needed —— that Bashisms be avoided in startup scripts.
Meanwhile, Dash is a POSIX shell meant for startup scripts.
It falls together.
/etc/portage/package.use/shell
app-alternatives/sh -bash dash
/etc/portage/package.accept_keywords/shell
app-shells/zoxide ~amd64
app-shells/fish # decent completions,
# for when I use sudo
app-shells/ohmyzsh ** # for my perfect theme