Hi, this is the first time I subscribe to the list, I usually read it
and I wasn't sure if I should write here or in the git repository.
I have an idea in mind that took me years to write it, it is based on
the following "TeX-SX" questions/answers:

Stack datastructure using LaTeX (https://tex.stackexchange.com/q/45946/7832)
LaTeX equivalent of ConTeXt buffers (https://tex.stackexchange.com/q/5338/7832)
Storing an array of strings in a command
(https://tex.stackexchange.com/q/215563/7832)
Collecting contents of environment and store them for later retrieval
(https://tex.stackexchange.com/q/184503/7832)
Collect contents of an environment (that contains verbatim content)
(https://tex.stackexchange.com/q/373647/7832)

Many times it is necessary to write in temporary files and then
include them in different parts of a document, for that is the great
package "filecontents" (SP) or much better, the latest version of the
package "filecontentsdef" (JFBU) to which kindly the author added the
ability to store content (including verbatim) in a macro without
having to write in temporary files.

Since "expl3" has an excellent way of storing data with l3seq and has
the ability to write files, it would be a great contribution to have
an official package from the LaTeX3 team that brings these ideas
together.

I have tried to unite everything in a single package "scontents"
(Store LaTeX content in Seq), totally amateur, as I am not an author
of packages probably the code is not entirely correct and may never be
public.  Of course it depends on "filecontentsdef" and "fvextra", I
think that the dependence on "filecontentsdef" could be changed to
100% code "expl3" and leave the dependence on "fvextra(fancyvrb)".
If this list is not the right place to write, let me know, if the idea
I present is functional and can be improved would be great.

Greetings to all.