It seems that Frontend developers have discovered the typical “Data Access Layer” that was used a decade ago in the Backend development.
When you discover Microservices you will find out that each component could get and manage its own data, so it’s fully reusable by its own.
If you are looking for examples on how to use Auth0 with Vue 3.0, please check out the following code samples 
Vue 3.0 + JavaScript:
Vue 3.0 + TypeScript: