Imo if you spend a little while using a shell like Xonsh or Ammonite, it becomes clear why the internal DSL approach is not as suitable for this as a new langua

Imo if you spend a little while using a shell like Xonsh or Ammonite, it becomes clear why the internal DSL approach is not as suitable for this as a new language that is designed with interactive shell usage in mind from the start. (Lisp-y languages might be a bit of an exception since command invocations are very close to the same thing syntactically anyway. But idrk since I've never tried using an internal DSL in a Lisp as a Unix shell.) But sure, some people do use and love Xonsh, and you could make the case for using a Xonsh builder in this way as well.