No.
I think the last thing he needs is steeper terrain. I wouldn’t worry about his hands and I’d work on that stance. Get his feet closer so he can balance on one ski at a time.
^^^ This. This. This. This! Yes to everything Erik just said.
--No poles yet. No! Poles are for parallel skiers. Use them as a reward for skiing parallel like a big kid.
--No to steeper terrain. He'll go even wider in his stance because he's using stance width and the braking snow plow now to slow down. He is not ready for controlling speed on something steeper yet.
--No to trees, no to bumps. Wait until his stance is narrower, almost parallel between turns. He'll have much better control of his turn radius with a narrower stance, especially if he can get skis parallel between turns. Controlling turn radius is important when there are obstacles in your line.
This big issue of stance width has to do with speed control. He needs to be able to go slow, to avoid obstacles, and turn on command. That wide stance is inhibiting these skills.
--Work on controlling speed by completing turns on these groomers, instead of relying on the wide braking wedge. Completing turns means going across the hill towards trees at the end of every single turn. This will slow him down every single turn. He needs to know and feel how this works, and choose to use it on purpose. He's young. This may take time.
--Once he "gets" that going across the trail will slow him down, work on getting those skis parallel between turns. There are drills that work for this. The longer he stays in that wide wedge, the harder it will be to break him of this habit. Work on completing turns and getting parallel between turns right now.
--The way to get skis parallel is to stand on the downhill ski between turns and move the lightened uphill one to parallel. Work on that with him, using the usual drills. Change instructors if you can't convince this current one to help him move towards parallel right now. This needs to be done on the easiest terrain he's on, so he won't insist on the wide wedge for speed control and a sense of security. Once he's on the outside ski between turns, he's ready to be on it for the whole turn. That means he can start working on fully parallel turns. With those, he'll have much more control of his turn radius and be ready for steeper terrain, and bumps, and trees.
Oh, and as a reward, poles. Let steeper trails, trees, bumps, and poles be a reward. In which order depends on terrain and reading the child's skills and confidence level. Poles can wait until parallel is happening. That's the big prize.