TYPO3 Core

When using composer, "extension handling" (storage and PSR autoload handling) is delegated to composer completely. That's why in composer mode retrieving extensions from TER as ZIP to be placed in typo3conf/ext is denied - composer stores extensions to vendor directory and symlinks to typo3conf/ext instead.

Thus, using the introduction package in composer mode on command line, it's required to add that to composer.json by using

composer require typo3/cms-introduction

Thus, the a composer install plugin would have to list available distributions (being available as composer package)...

It needs to be

composer req typo3/cms-introduction='*'

Maybe we could advertise a newbie-friendly TYPO3 directly in the docs, https://get.typo3.org and similar pages like https://ddev.readthedocs.io/en/latest/users/cli-usage/#typo3-quickstart?

composer create typo3/cms-base-distribution=^9 . && composer req typo3/cms-introduction='*'

I am really thinking about an easier "try out TYPO3 now"-experience.
What do you think?

In this way the distribution installs its dependencies but does not create the example database records.

I did not find a way to run its update script otherwise through the backend - am I missing something?

So it should also be noted that one needs to deactivate/activate the introduction extension.

So to get going in the shortest time it would be:

composer create typo3/cms-base-distribution=^9 . 
composer req typo3/cms-introduction='*'

vendor/bin/typo3 extension:deactivate introduction
vendor/bin/typo3 extension:activate introduction

touch public/FIRST_INSTALL
#  then go to ..../typo3/install.php

As this technically not solvable with composer in the same easy fashion as without, I suggested to mention the introduction package in the "Quick Install" guide:
https://docs.typo3.org/m/typo3/guide-installation/master/en-us/QuickInstall/TheInstallTool/Index.html#the-install-tool (PR https://github.com/TYPO3-Documentation/TYPO3CMS-Guide-Installation/pull/134)