If the DMG states you cannot use Fast Hands with any item that requires an action to activate, but this Errata states you can use Healers Kit with fast hands WHICH requires an action, who am I supposed to listen to?
Also, What is defined as Use an Object?
Activating some magic items requires a user to do something special, such as holding the item and uttering a command word. The description of each item category or individual item details how an item is activated. Certain items use one or more of the following rules for their activation.
If an item requires an action to activate, that action isn't a function of the Use an Item action, so a feature such as the rogue's Fast Hands can't be used to activate the item. (DMG PG 141 "ACTIVATING AN ITEM")
Can a thief use the Fast Hands feature to activate a magic item? No. One of the benefits of Fast Hands is being able to take the Use an Object action as a bonus action, but using a magic item doesn’t fall under Use an Object, as explained in the Dungeon Master’s Guide (p. 141). In contrast, using a nonmagical item, such as a healer’s kit, is in the domain of Use an Object. (Sage Advice Compendium v1.03)