Is it possible to set the desktop wallpaper or background to something dynamic? e.g. very large image that supports zooming and scrolling, gif etc
Specifically, what options exist on Windows that work like Active Desktop back in the day?
It mostly depends on the platform and the software providers, but can be generally categorized into two heads.
Supported via 3rd party app/extension.
The first category consist of desktop/mobile OS (mostly latter) which provide native support for dynamic/animated wallpapers. Some examples are modern iOS devices and various Android phones running proprietary ROM with animated wallpaper feature. This category too can be bifurcated into two heads where either a fixed set of animated wallpapers are available or user can supply their own dynamic image.
Second category consist of enabling dynamic wallpaper support by installing 3rd party app. This is mostly available in desktop OS. You can do a Web search to find tools for desired platform.