Comment by okaleniuk

I love it!

In fact I employed the same idea for the slide stack site I use for teaching. Not exactly "URL is an app" but "URL is a slide"

https://okaleniuk.codeberg.page/blackboard/_1.html?sequence=...

The same consideration applies. No backend, no storage, also no user data collection, no authorization, no hurdles in general. Everyone can use it.