Android devices support screen effects - tweaking beyond you could thought of through accessibility features. Several apps demonstrate this capability, such as the "Darker" app, which allows users to reduce screen brightness below the system's minimum level - similar to the Extra Dim feature found in Pixel phones. This accessibility feature is versatile enough that some apps even use it to create visual effects, like simulating a cracked screen display and possibly blur effects also. So implementing additional screen blur functionality is definitely possible on Android devices, but for other platforms its not possible to such thing, don't even think of iOS or macOS might be possible for desktops but for that you must have deep understanding of display managers and window managers in Linux, windows.

You can find code from these kind of apps if they are available on Github.

Projects that i found: 1.lowbrightness, 2.screen-filter

Let me know if this is helpful or not 👍