From my recent foray into modern Django world, most simple projects and MVP start out as server side like the official guide. Then, when people need some extra frontend magic like React and/or SPA, it's pretty easy to insert into Django. You just include the bundled React/Vue app into a js script still included and served by the same Django route/view/template. Of course, it's also common to start transitioning to Django Rest Framework (DRF) as your API points.