In general: battery life, difficulty of fitting, limited usefulness for the costs. Also, for your task, you’d need the precise location of your subject, or hig

In general: battery life, difficulty of fitting, limited usefulness for the costs. Also, for your task, you’d need the precise location of your subject, or highly reliable obstacle detection (including “there’s nothing, not even a good path” obstacles), probably both. The latter sort-of works for self-driving cars, but their computers are rather big to carry around, and they can declare anything “clearly not a road” as “obstacle”. They don’t have to recognize a small footpath across a mountain ridge, or alongside a river.