I had a similar issue. Followed all the instructions by Apple on preparing the laptop for a new owner: https://support.apple.com/en-us/102773 and then gave it to the neighbor's kid for their school. It has the whole hello page, but turned out they had to login as me first. The standard part was that the laptop contributed being listed on my devices and I couldn't remove it, UNTIL we logged in once again as me - after a full wipe. I figured either I messed up the process or got stuck in an edge case flow. Either way, it would have been very annoying if the new user wasn't living close and somebody I knew.