[Vuejs]-Is there a way to fully open the v-dialog before the list is is loaded?

The dialog doesn’t open instantly is because your list takes time to render. A good way to improve your UX would be to add a fixed height to your dialog and use Vuetify’s skeleton loaders (https://vuetifyjs.com/en/components/skeleton-loaders).
These improve user experience by bringing about an illusion of loading.