npm i preact-markdown

import Markdown from 'preact-markdown';
render(<Markdown markdown={'**Hello** _World_!'} markupOpts={...} markedOpts={...} />, document.body);

h(Markdown, {markdown: '**Hello** _World_!', markupOpts: {...}, markedOpts: {...}})
// or simply:
Markdown('**Hello** _World_!', {markupOpts:{...}, markedOpts:{...}})