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Ok, built-in movements (most of them) and animations are handled automatically by Movement Timer (Fusion's DeltaTime), so if you "pause" them by setting the coef to 0 or something, and you needed other objects or animations to play, you would need to have a custom system in place, something not tied to deltatime (at least not the extension's one).
DeltaTime for custom movements, custom timers, etc, is easy, all you need to do is to multiply any addition or subtraction by deltatime, and if that value was just 1, you can replace the one entirely by deltatime.
The idea of using this for a pause system is certainly an intriguing one, and I've thought about it as well.
Here's a great guide I've helped a while ago: https://gamejolt.com/p/guide-deltatime-yqhsba5q
That should hint you on how to use DeltaTime in general, and if needed, you can implement secundary deltatimes, not affected by Fusion Movement Timer, meaning they could run independently, so for example, lets suppose you "pause" built-in movements and animations by setting the coef to 0, then for the pause menu stuff, you could use a custom deltatime, detached to the Movement Timer, this way it wouldn't be affected whatever changes you made to the "time speed". But if you want to keep things simple, you can skip deltatime entirely for elements that wouldn't be paused, but I don't recommend as usually when you use deltatime, it is desirable to either have a unlocked framerate (framerate 1000, vsync off), or use the maximum framerate the monitor can display (this is safer btw, framerate 1000, vsync on).
Events are not tied to deltatime, but there are ways of making what people call a "fixed deltatime", updates on the same pace, no matter the framerate.