Yahweh appointing the Levites to help Aaron is spoken of as if they were a gift that Yahweh were giving to Aaron. AT: "They are like a gift to you" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Here "given" to God represents being set apart to serve God. This can be stated in active form. AT: "which I have set apart for myself" or "and I have set them apart for myself" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-activepassive]])