I don't understand the hype around Gatsby and co. Here in France everyone uses wordpress/drupal + docker and boom. This combo works great and there is no need to reinvent the wheel.
In college we were always taught to do TDD on large projects, and everybody I know does TDD(at least here in France). I can even think of working on a project that's not TDD. You need to look up Agile, Clean code and Xtreme Programming ;-)