Vue3 Dynamically Create a Service Component

In Vue2 I could create and instantiate a Component like this

var service = new Vue({
   data() {
     return {
       example:2,
     }
   },
   computed:{
     score() {
        return this.example * 10;
     }
   }
})

//Returns 20
console.log(service.score)

I understand that this functionality has been removed from Vue 3. But i still require the ability to instantiate components with reactivity, computed functions etc without adding them to the DOM.

Is there a way to do this in Vue3?

I’ve tried createApp, defineComponent, defineAsyncComputed to no avail. And don’t really want to write my own javascript class with reactivity and getters, setters and event listeners…