org-reflect

With Org Reflect you can mirror the contents of source files into a target
org file. When the contents are code, they are automatically wrapped in an
Org Src block (but this behavior can be disabled, if you want).

Before being displayed, filters can be applied, such as restriction of line
ranges and the processing of the text through Emacs Lisp or Shell script
filters of your choice (write any functions you want).

Therefore, Org Reflect can embed parts of files into your Org document.
This is convenient, and it can be instantly updated.

It’s particularly useful if you are producing documents that quote from
other documents — so you don’t need to copy-paste. Moreover, unlike the
#+include tag from Org Export, you can visualize the results, which are
actually copied to the target Org file itself as displayed.

For all the details, please do see the README

Open it easily with:
  (find-file-read-only "README.org")   <--- C-x C-e here¹

or from any buffer:
  M-x org-reflect-see-readme

or read it online:
  <https://flandrew.srht.site/listful/sw-emacs-org-reflect.html>

¹ or the key that ‘eval-last-sexp’ is bound to, if not C-x C-e.

(See also the docstring of ‘org-reflect-write’.)