Se o DMG declara que você não pode usar o Fast Hands com qualquer item que exija uma ação para ativar, mas esta Errata indica que você pode usar o Healers Kit com mãos rápidas O QUE requer uma ação, quem devo ouvir?
Além disso, o que é definido como usar um objeto?
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)