They require different approaches.

The best way to herd cats is by a laser pointer: show a clear, shining goal, and you don't need to give more directions.

With sheep, you need to run circles around them and so drive their formidable grass-cutting capacity where you want it to be, slowly.

Nice analogy. I like that. For the laser you likely need to show an indicator for the distance to the bright red spot, and break it into measurable chunks (like a roadmap) to which actionable steps can be attached. Tbh a cat won't do anything with that, but to the feline breed of FOSS developers it may help to keep (and understand the importance of) product focus. Although you might just focus the bright spot on farther away objectives when the felines get closer to it, to refocus their attention.

Bright light in the distance works for me. A lot of the interest is in the path finding process - dead ends and cycles included. A bright light in the distance that someone else has broken into measurable chunks is totally unappealing.

Like JC said - you can shove your roadmaps where you like, many people contribute exactly because they're sick of roadmaps and product foci.