I want to keep this feature request a little open-ended because other software has handled it in different ways. Currently PixiEditor only allows the entire timeline to be exported as an animation (or as frames).
For game dev, it’s way more convenient to have all your animations in the same document. Aseprite has a system to tag various animations along the timeline and export them individually.
Krita does not have a way to tag animations, but it does have a way to create named groups of layers, along with tools to export groups individually. Which can be used to group animations in a less intuitive but more powerful way.
In the most complex scenarios, a single document may have multiple animations for multiple objects all of which may need to be exported separately. EG a character customization system where you have 10 different shirts all which have a walk animation that perfectly overlays the player’s walk animation. In this situation, a combination of groups and animation tags, or even nested groups could be used