async function getItems() {
    let response = await fetch('/api/items/all')
    let json = await response.json()
    return json
}

<div x-text="JSON.stringify(getItems())"></div>

// or alternatively:
<div
    x-data="{
        items: {},

        async getItems() {
            this.items = await (await fetch('/api/items/all')).json();
        }
    }"
    x-init="getItems">
</div>