3 courses match your filters.
Learn Go from the type system up: structs, methods and interfaces, then slices, maps, errors as values, and goroutines with channels.
Go · Concurrency · Interfaces · Backend
Output-based
Learn C from first principles: types and control flow, functions, then the part that makes C different — arrays, pointers and manual memory.
C · Systems Programming · Memory · Pointers
Output-based
Null safety, data classes and coroutines on the JVM.
kotlin · null-safety · data-classes · sealed-class
Output-based