Sounds like you want a perfect, not good, set of goals. It's infeasible to choose a perfect setup up front -- try an agile/iterative approach. I think you're smart, so I believe in your ability to pivot later if you change your mind. And it won't be a disaster or embarrassment if you choose wrong.
You know how great writers say they clear their writer's block by just starting?
I recently heard someone say their favorite cure to writer's block is to read more and do research.
I found something profound about that. Writing is hard when you don't have anything to write about, and maybe there's something analogous to be said for goal setting.
You know how great writers say they clear their writer's block by just starting?