I apologize in advance if this feature is somehow there without me seeing it, or if there is already a similar suggestion.
I think it could be beneficial to have animation frames be groupable. I know right now we can specify start and end frames as far as viewing animation sequences, but this is more detailed. We would be able to group say frame 1 - 4 for walking, 5 - 10 for running, 11 - 14 for jumping, and so on.
These groups would be collapsible making it easier to view them. It would all be within the same project so no going back and forth. They would be selectable in order to automatically set the start and end frames to the ones defined as the group in a single click. And all things pertaining to animations would use these, for example, exporting to sprite strips, onion skinning, and anything else I’m not mentioning where it makes sense.