EXT:bootstrap_package for site-package aka theme build on Bootsrap 5.
EXT:modules for user plugins like user-profile, registration, user-addresses, and more.
EXT:shop for the whole shop functionality.
EXT:questions for the FAQ page and FAQs attached in the product detail views.
EXT:glossaries for the glossaries and definitions.
EXT:fluid_fpdf for generating invoices, delivery-notes, product-sheets and more.
EXT:parsedown_extra for rendering the extension documentations from markdown to HTML.
* There are only build-in settings made using site-settings & TypoScript – no templates or other files were changed or overridden!