You are correct; Material-UI extends beyond React and offers a versatile toolkit for various front-end requirements.
As for using Google's Material Design for a startup, it depends on the specific branding strategy and goals of the company. While Material Design provides a polished and professional aesthetic, some startups may prefer to develop their unique design language to stand out. However, the customization capabilities of Material-UI allow for extensive branding modifications, making it a powerful tool regardless of design preference.
Your input is appreciated.