This is meant as a kickstarter to test https://review.typo3.org/c/Packages/TYPO3.CMS/+/64021 during review and to serve as a showcase for using AssetCollector/AssetRenderer events later.
If you just want to have a quick look around, you can start it with DDEV-Local:
ddev launch
You can also download it or install via composer into your test installation:
composer config repositories.asset-post-processing vcs https://github.com/TYPO3-Initiatives/structured-asset-rendering.git
composer config minimum-stability dev
composer req typo3-structured-content/asset-post-processing:dev-master
No further configuration needed.
After installing it registers some assets (in ext_localconf.php). You can also register assets in Fluid with <f:asset.css> and <f:asset.js>.
It registers some EventListeners in Services.yaml. They get called before assets are being rendered.
It reports in the frontend which listeners were executed.