Scribble tools (no warranty animation tool)
Hello, I used this script to do several projects of mine. It is similar to after effects vector paint.
It converts grease pencil strokes and animates them. If the grease pencil layer has only 1 frame, it uses the build modifier so the result looks like a recording of the drawing process.
If there is more frames, it converts it into animation by the frames.
In both cases it adds a controller gizmo. It is especially usefull to change timing of the gp layer frames.

Install - copy the script into scripts/op/ directory, not into addons, this does not have any typical addon structure.

operators(in the n-key area of 3d view):
Convert stroke - does the conversion, options are below it
Hide animate widget - adds the same widget to any set of selected objects
hierarchy operators - these are used to work with the sets of animated frames, since some are always hidden, so duplicating-deleting or moving to other layer is hard, these make this possible.

as said in the title, there is no warranty, or support nor anything with this.
I posted it only for the case somebody else would be interested in such a special feature.

Could you provide an example blend or movie?

Sounds cool.