There is an important concept to understand about how the Agile Tools OKR platform approaches goal setting on a personal/individual/employee level.
Agile Tools does not use the term "level" to describe OKR relationships as it sounds and encourages hierarchy, which we want to minimize in modern organizations. Any organization will have management and departmental hierarchy; that is a human cultural fact.
You can create OKRs for three major scopes: Team (preferably cross-functional), Value Unit (your products, projects, services, etc.), and Organizational Unit (company, sales department, branch, plant, etc.).
And here comes the crux of personal accountability in any OKR - every Goal must have an owner, just one. And, every Key Result must have a caretaker (one or two). This concept is where the rubber meets the road - how any individual/employee contributes to shared goals, even company vision.
As an owner of an Objective, you are accountable for its achievement. When Key Results are created, the Goal (Objective) owner is also responsible for any of its Key Results by default. You can delegate the responsibility to achieve any single Key Result to a different person, a so-called Key Result caretaker(s), two, at most.
We promote shared goals, not personal ones.