How to export a note as plain text file?

I would like to use notes as plain text files to edit them with

basic editor of text files like `vi` or `emacs` and to deal with

them with command line tools ( `grep`, `awk`, `perl`… ).

How may I perform such an export to either ISO-8859-15 or UTF-8 basic text format

which is a format I can use on all my environments ( mostly command line interface,

many macOS versions, Linux, FreeBSD… )?

A command line like `iconv` doesn't seem to be able to convert them.

iconv -f ISO-8859-1 -t UTF-8 my_note.txt >my_note.utf-8

produce a file which looks like utf-8 encoded, but is unreadable.

A simple copy-paste from `Notes` toward `vi` is working, but doesn't

scale on huge notes.

Any solution based on command line would be perfect.

A solution working on any version of macOS fromm Big Sur to Sonoma would

be preferred.

Thank you for any kind of help.

[Edited by Moderator]