Ukraine is becoming one of the largest armies in the world, and one of the two with big intensity war experience. They lack equipment and some training, but they have a lot to teach nato and a lot of manpower so nato citizen don’t have to go to war in the near future.
They also were controlling a strategic piece of territory, which is why Russia invaded in the first place. Access to Mediterranean Sea. There’s nothing the US love more than to have their enemies surrounded and blockades by US vassals. You know like Taiwan for example.