The gaseous form spell's description has the following relevant text:
You transform a willing creature you touch, along with everything it's wearing and carrying, into a misty cloud for the duration. [...]
While in the form of a misty cloud, the target can't talk or manipulate objects, and any objects it was carrying or holding can't be dropped, used, or otherwise interacted with. The target can't attack or cast spells.
The first sentence of the spell description makes it clear that the affected creature's equipment is included in their new form, and the latter paragraph makes it clear that the creature cannot actively use equipment. However, it's unclear to me to what degree they benefit from their equipment's passive benefits.
Does a creature retain the benefits of equipment while affected by gaseous form?
- As a mundane example, say that the creature had a suit of plate mail and a shield equipped – do they gain the AC benefits from both, only the armor, or neither?
- What about if they have an active magical effect like the darkvision bonus from goggles of night? Can they still see in the dark while transformed?