1.Select all bones in Pose Mode.

2.Go to the menu in the 3D Viewport and select Pose -> Animation -> Bake Action.

3.Ensure these five options are set before clicking OK:

-Set the Start Frame.

-Set the End Frame.

-Check the box for Visual Keying.

-Check the box for Clear Constraints.

-For Bake Data, select Pose.

This should consolidate everything into a single action.

One of the ways to further utilize animation assets in Blender is to split actions. Here is a step-by-step guide on how to split actions.

Step 1: Baking the Animation

First, bake the animation in Blender. This involves solidifying the animation data and making any necessary adjustments such as removing root motion. For detailed instructions, please refer to this link.

Step 2: Preparing a Text File for Action Splitting

Prepare a text file in the following format to split actions:

WalkForward:10-40

WalkRight:50-80

If the format of the animation names in the text file differs (e.g., "10-40 WalkForward"), please adjust the format using the script provided at this link.

Step 3: Using the ActionMaking.py Script

Open the ActionMaking.py script from Blender’s text editor. Set the file_path to the path of the text file prepared in Step 2, and set the original_action_name to the name of the action you want to split.

Step 4: Running the Script

Select the target armature and run the Run Script. This will appropriately split the specified action based on the text file, making each action available as a separate item.

Unity

1. Export FBX from blender with binary(off Armature->AddLeafBones).

2. Drag and drop the FBX file to the Unity.

3. Set the Root to the rootnode.

Unreal

1. Set the frame rate 30fps.

Export FBX from blender with binary(off Armature->AddLeafBones).

2. Import the fbx file to 3dsMax with unit  as meter and chose Animation->Extra Options->Animation Take(usually *ArmatureAction), check Geometry->Smoothing Groups. 

3.Delete the armature.

4.Export the FBX with unit as automatic, check Geometry->Smoothing Groups.

5.Drag and drop the FBX to UE4.

To import the animation check "Use default settings".

However, in the unit system of UE 4, the size of the mesh is about one hundredth.

The procedure to change the scale of the model is posted in the following article.

http://eizouasobi.blogspot.com/2019/01/how-to-change-scale.html

Animation editing within Blender

How to transfer root bone pose animation to the animation of the entire armature

https://eizouasobi.blogspot.com/2024/05/blender-python.html

How to bake action:

https://eizouasobi.blogspot.com/2024/04/how-to-bake-actions-in-blender.html

How to split action:

https://eizouasobi.blogspot.com/2024/04/how-to-split-actions-in-blender.html