Fish equivalent of bash $(command) notation

Since fish 3.4 (released March 2022), $()-substitution is supported. It works the same as ()-substitution, but can be used inside double-quoted strings.

FYI: If you additionally need to use this inside a string:

echo "Found "(count $PATH)" paths in PATH env var"

In fish, $ is used only for variables. Correct notation equivalent to bash $(command) is just (command) in fish.