Hello John, thanks for reaching out!
You can add any type of valid oEmbed URL to an Embed field, and if it's not compatible the other option is exactly that; using the preformatted option of the Rich Text field to add your iframe as code.
Then in your project, you'll just need to render that piece of the Rich text field as HTML. Use dangerouslySetInnerHTML to template the result:
import React from 'react'
const VideoComponent = ({ videoIframe }) => (
<>
<div dangerouslySetInnerHTML={{ __html: videoIframe }} />
</>
)
export default VideoComponent