Describe the feature in detail (code, mocks, or screenshots encouraged)

• There are many examples of this
• Idea is to create a component that only shows a subset of a large number of list items
• Individual item layout is fully customizable
• Supports both fixed size and variable sized items

What type of pull request would this be?

None

Provide relevant links or additional information.

• https://codepen.io/zupkode/pen/MWwgLyb
• https://github.com/v1ack/svelte-virtual-scroll-list