`cb[uffer]` processes the current buffer as a compile buffer, which will find `grep` format matching lines (i.e., at a minimum starting with `<path>:<line-number>:<column-number>`) and populate the quickfix list with them, and jump to the first match.

E.g., your example doesn't do anything because `ls` doesn't output `grep` format lines. So try piping the output of `grep` (you'll need flags for the line number and column number with `grep`, hence the `--vimgrep` flag above) matching the above format (or you could try `ls | sed 's/$/:0:0/' | vim -c cb -`, which will hack `ls` output to grep, and is occasionally useful).

(Note that the above hints at another useful tip, `grep` parsing is only part of what `cb[uffer]` does, it can also parse compile output, e.g., something like `gcc foo.c | vim -c cb -` will jump to the first compile error in your program and put the rest of the errors in the quickfix list).

You get similar buffer behavior if you use :make inside Vim and Vim as your build terminal. Despite being named :make it isn't hardcoded to just make as build tool (there's a bunch of out-of-the box settings you can pick with :compiler or you can update individual settings like makeprg).

Similar behavior with :grep inside Vim which you can change your grepprg to rg if you like.

I've got a feeling the `| vim -c cd -` isn't as commonly known because the Vim-initiated versions are somewhat more commonly known. It's handy to know that vim can do it in both "directions" (initiated from the external shell / initiated to the internal shell support).