The icon alone carries no meaning, so it needs aria-label="Open menu" (or a paired text label) and aria-expanded to announce its state. The three lines morphing into an X visually reinforces that the state changed.
It's closely tied to the drawer entry — a hamburger menu is only the trigger icon that opens that drawer, not the drawer itself. They're always paired but remain separate components.
It's a long-standing mobile convention, but critics note that with only 3–4 menu items, leaving them visible outright often beats hiding them — a hidden drawer only gets opened by people who already know it's there.