The premise is using Notion and Figma’s (or any other design software, really) public link-sharing features to use a live website to easily design and update signage remotely.
For example, depending on your use-case, all you need is a device that connects any display to the Internet and you can update the display contents from anywhere you’re signed into your account.
Great example would be a raspberry pi in a wall-mounted enclosure with an e-ink display for QR codes, semi-permanent door signage, pricing information, menus, etc. all with the freedom of custom designs and info that will update changes live as you make them.
With all of these tools, there’s also a lot of potential for interactive kiosks or help-desk style interfaces. Notion is inherently interactive with Blocks like Galleries and Toggles, but by using Figma’s Prototyping feature, it’s relatively straightforward to design a custom navigable frontend interface (with animations, GIF, and video playback) for touch kiosks, tablet signage, etc. all while being able to work with others collaboratively and make live updates on the fly.
For more advanced or particular scenarios, I could also see this being used with an interactive 3D web viewer like Spline to create live signage with 3D elements, lighting, or even interactivity on a multitouch display. Think 3D floor plan map of a building or interactive 3D informational product displays at retail stores.