Hey there. D1 -> D2 migration took place automatically for all qualifying accounts back in 2017. I believe there was a cutoff for the time you had to actually start D2, or else you'd start out fresh. If the characters don't automatically appear, there is nothing that can be done now. It has never been possible to migrate items owned in Destiny to Destiny 2. The in-game reason is that the Vault was destroyed by the Red Legion during the attack on the Tower. Only appearances migrated, as well as being given a few exclusive emblems based on D1 history.