Yes. An approved handheld calculator is permitted for the entire Math section, and Bluebook also has a built-in Desmos graphing calculator. Most students who have practiced with the built-in Desmos never touch the handheld, but bringing one as a backup costs nothing.
The honest advice is to practise on whichever one you intend to use, and then bring the handheld anyway. Switching tools on test day is where the time goes, but a dead battery or an unfamiliar interface is a much larger risk than the weight of a spare in your bag.
The full picture, with the surrounding detail, is in SAT Test Day, Hour by Hour: What Actually Happens.