I also got a 400 for my kid. It was an ok experience, but I had reliability problems. Just wouldn’t turn on consistently! This made it frustrating for the kid to engage with even though he enjoyed it when available.

I think the problem was a compatibility issue between the Pi’s video output and the old TV I was using as a monitor. I used a fresh micro HDMI to full HDMI cable as a direct connection, but still took a lot of fiddling to get it on.

Now I’m building a full sized PC for him. We built a KBDcraft Adam keyboard for it together, which he really enjoyed https://kbdcraft.store/products/adam