animate part of the way along Follow Path I want to have an object Follow a Path until some percent of the path and then stop Follow Path:

I can set the frames to animate the path:

and the offset time to start the animation:

But I don't see a way to stop the animation (small cube towards large cube) when it is part-way along the path.  I created and aligned the objects and path with the empty objects (in blue), so that they would all be aligned.  And actually it would be better if I could stop the animation at some intermediate path vertex.
In 3ds Max, I am able to frame-key % path, so that I can speed up and slow down a path-based animation.
How can I accomplish this?
Change your follow path constraint like this:

Then keyframe offset from 0 to 0.8

Result:
https://youtu.be/6IdUgpwBVgw