Solution: Run a command

Here is a possible solution to the task.

Code

run 'echo', 'home:', '$HOME';

🦋 You can find the source code in the file run-a-command.raku.

home: $HOME

run launches echo directly, passing each string as a separate argument. With no :out, the program’s output goes straight to the screen.
The argument reaches echo exactly as written: $HOME is printed literally, not replaced with your home directory, because no shell is involved to expand it. This is why run is the safe default — the same command given to shell could behave very differently.
To actually print the home directory, let a shell do the expansion: shell 'echo home: $HOME' prints something like home: /home/anna. (Keep the single quotes on the Raku side, too — a double-quoted "$HOME" would make Raku itself try to interpolate a variable named $HOME before echo ever runs.)