The Rust API is not as friendly or rusty as it could potentially be, one thing that stuck out to me as a large contributor to this is the need to call headless::init() then headless::shutdown(), the Rust type system is able to express this in a more concise and friendly manner: create a struct that represents a session, say HeadlessSession, and implement all initialisation within a new associated function (static method), then impl Drop for HeadlessSession and place shutdown behaviour in drop there. In this way, the lifetime of the session determines its validity in a way that the user is not required to remember anything, the user can drop it if they need to manually end a session or simply allow it to go out of scope normally.

Any configuration options can be placed as arguments to new with a SessionConfig struct, and any state that needs to be communicated can be placed behind getters on this struct, in this way, manipulations of the Binary Ninja instance can be consolidated into this struct, and the receiving of state information can be too.