Using Vue 3 with Razor pages as templates: Data transfer in/out

We're in the early stages of migrating from angularJS to use Vue 3 in conjunction with Razor .cshtml templates, but we seem to have hit a bit of a roadblock.

Where in angularJS we had controllers to handle accepting and initialising scoped variables, we're struggling to do so in VueJS due to its one-way data flow.

We have data coming from the .cshtml models that Vue obviously has no clue about and no way to do an ng-init equivalent (I've tried making a custom directive to assign a value to a data property but it won't stick for some reason)

At the moment we're using scoped slots to act as a pseudo-controller (or, an adaptation of option 1 here https://chowson.github.io/vuejs-sitecore-mvc/) :

ImageGalleryController.vue

<template>
    <slot :imageData="imageData" ></slot>
</template>

<script>

    export default {
        name: "ImageGalleryController,",
        data() {
            return {
                images: [],
                imageData: {
                    selectedIndex: 0,
                    setIndex: this.setSelectedIndex
               }              
            }
        },
        setup() {
        },
        methods: {
            setSelectedIndex(index: number) {
                this.selectedIndex = index;
                return
            }
        }
    }
</script>

And then in the .cshtml:

_ImageGallery.cshtml

<image-gallery>
    <template v-slot="data" class="product-image-gallery">
        <div class="row image-gallery-row">
            <!-- A mix of razor and vue code goes here--> 
        </div>
    </template>
    </image-gallery>

Formerly in the above code we'd have had something like ng-init(@Newtonsoft.Json.JsonConvert.SerializeObject(images) (where images have been retrieved from the database)

I suppose the real question is whether there's a more elegant/not-hacky way to pass data from/to vue components to "external" templates?

It feels like we're breaking Vue, but I'd rather not sacrifice the benefits of having partially server-side rendered pages.

Also concerned that we'd potentially be passing a large number of objects through to the slot which doesn't feel right.

Thanks