Not quite what you need but maybe use the markdown card ?
type: markdown
content: >-
The **Markdown** card allows you to write any text. You can style it **bold**,
*italicized*, ~strikethrough~ etc. You can do images, links, and more.
For more information see the [Markdown
Cheatsheet](https://commonmark.org/help).
alternatively to pull in html from an external source : iframe