HTML is poweful technology. This technology can be used not only for webpage generation. HTML is also can be used to generate scrolling text messages.
Scrolling text messages a.k.a marquee is way to hidden and silent information transfer.
Marquee is useful as alternative to voice, messagers, SMS, phone calls and Wi-Fi. Can be used by people which are locked in rooms and vechicles (in case of quarantine for example).
If you wish to scale marquee size above physical device dimensions you can use lenses. Lenses can be placed between receiver or can be placed between projection surface. You can use Fresnel lenses as alternative to regular lenses.