We use Moodle to handle assignments and grades in a few dozen high school classes and it works well. It is terrific for students to always have feedback of how they are doing, whether they are missing assignments, etc.
If you weight grades, you will typically want to give it a category of "uncategorised" until all students have been graded, and then switch the category to one of your graded ones like "daily work", etc. That may get at what you wan.
But you can hide an assignment while you are marking it. During that time, student's can't see it nor their grades.
Having said that, we don't hide assignments during the grading process. The issue is that student's can't see the assignment being graded in the course list which means they can't turn it in late, and it might be unclear why it disappeared even if you don't accept late work. But the above option of hiding it is available if you want to go that route.