Several restaurants on one site
One script tag and no launcher. Each button opens the widget for its own restaurant by passing that restaurant's key to NovelWidget.open().
Live example
Snippet
<button type="button" onclick="NovelWidget.open('5631dfc5-5aef-4de0-a9b0-b6e66da37b50')">Book at Restaurant</button>
<button type="button" onclick="NovelWidget.open('dc36e3f6-0cb5-44f1-928c-ea379a077e07')">Book at Test Restaurant 1</button>
<script src="https://widget.withnovel.com/5631dfc5-5aef-4de0-a9b0-b6e66da37b50.js" async data-manual-open="true"></script>