Definitely it's acceptable practice.
Vue can be used for single-page apps, but there's nothing wrong in using it in a traditional multiple page-based application. In this context, one Vue app can be one "widget" on such a page, big or small.
The need to have one "central" component will come the moment you'll require sharing data between multiple components. You'll probably get there - but you don't need to worry about it now.
In fact, one of major advantages of Vue is the ease of use in this particular setup. You can introduce it to your codebase step by step, start with a few components, and slowly make your way towards a modern app.
GitLab is known for going through a major progressive rewrite from jQuery to Vue, have a look at their story:
- Why we chose Vue
- How we do Vue: one year later
