Rubix Cubes are popular here. 2x2 for the younger 3x3 for the older.
Remote control something, but something strong enough to run on carpet, too.
Maybe a handheld digital game? Or something that can be played together or alone. I always hesitate with games for gifts for kids when I don’t know their family situation. If they don’t have someone else who can/will play with them, they have a useless gift that just reminds them that they don’t have anyone to use it with.
DS is 9 and really likes beyblades. There are sets that come with an arena that they could play with together.
Remote control cars.
ETA: oh maybe I made a wrong assumption the boys are related. If they aren’t I wouldn’t do the beyblades since it’s more fun to play with someone else.