I have just converted https://github.com/kozakdenys/qr-code-styling to a Svelte action and added support for reactivity.
You can find the options API documentation for kozakdenys/qr-code-stylinghere
Simple
<script>
    import { qrcode } from 'svelte-qrcode-action';
</script>
<div use:qrcode={{ data: 'this content of qrcode' }} />
With reactive
<script>
    import { qrcode } from 'svelte-qrcode-action';
    import { onMount } from 'svelte';
    let options = {
        data: 'qr content'
    };
    onMount(() => {
        setTimeout(() => {
            options.dotsOptions = {
                color: '#4267b2',
                type: 'rounded'
            };
        }, 2_000);
    });
</script>
<div use:qrcode={options} />
need better documentation