Unfortunately not; Scheduler is designed as an "activity module" in Moodle terminology, and that means that its data needs to be attached to individual courses (in fact individual instances of Scheduler in a course).
If you want teachers to offer slots to students across different courses, I usually recommend to create a "meta course", i.e., one in which all students are enrolled, and create the Scheduler there.
If you want teachers to offer slots to students across different courses, I usually recommend to create a "meta course", i.e., one in which all students are enrolled, and create the Scheduler there.