I have begun my fourth attempt to write a Tactical Guide to Pathfinder 2nd Edition. And I ran into a rules question in trying for an efficient action economy by minimizing Interact actions. Unfortunately, "Interact" is such a common word that I cannot effectively search for old posts with the answer. I did find the threads Is "Interact" problematic? and Interact, Manipulate and eventually description, but they don't answer my question.
Can a character Interact to open a door with both hands full?
INTERACT [one-action]
MANIPULATE
You use your hand or hands to manipulate an object or the terrain. You can grab an unattended or stored object, draw a weapon, swap a held item for another (page 268), open a door, or achieve a similar effect. On rare occasions, you might have to attempt a skill check to determine if your Interact action was successful.
Interact
You can use the Interact action (page 416) to:
• Draw, put away, or swap an item. You must be holding the item to put it away or wearing it to draw it. Swapping allows you to put away one item and draw another in the same action (such as putting away a dagger and drawing a mace). Abilities that specify what you do when you Interact only allow this if they say so; the Quick Draw feat lets a rogue Interact to draw a weapon, but doesn’t allow them to stow one as well. Swapping lets you swap only one item for another; if you were wielding two weapons, you could put away one of them and draw a different item, but you would need to put away the second weapon separately.
• Pick up an item from the ground.
• Pass off or take a held item from a willing creature. The creature you’re passing to must have a hand free. You can also attempt to throw an item to someone. You typically need to succeed at a DC 15 ranged attack with a 10-foot range increment to do so.
• Detach a shield or other item from you using one hand.
• Change your grip by adding a hand to an item.
• Retrieve a stowed item from a backpack, pouch, or similar container (or put one away). You’ll often need to Interact to open or close the backpack or container.
manipulate (trait) You must physically manipulate an item or make gestures to use an action with this trait. Creatures without a suitable appendage can’t perform actions with this trait. Manipulate actions often trigger reactions.
I see that Interact in general does not require a free hand because sometimes the character is Interacting with an item already in hand, such as stowing an item. Opening a door requires manipulating a door latch that is not already in hand, so does it require a free hand? Note that in real life, I have often opened a doorknob while my hands are full of bags of groceries, though this is slower than opening a door with hands empty.
The Reload rule says, "Reloading a ranged weapon and drawing a thrown weapon both require a free hand. Switching your grip to free a hand and then to place your hands in the grip necessary to wield the weapon are both included in the actions you spend to reload a weapon."
After the Remastering spellcasters no longer need a free hand to make gestures for a spell with the manipulate trait. For using a spell with a locus they either must be holding the locus or have a free hand to momentarily retrieve and put it away during Cast a Spell.
The players at my Beginner Box table asked me something similar to this the other day. I think it was if they could open a door with their hands occupied by a weapon and a shield. I told them it would depend on the situation. If they weren't in combat and in no danger I wasn't going to be a stickler about needing hands free for simple stuff like that when they could easily release their shield (which is strapped to their arm so not dropped), open the door, and wield it again before any potential enemies beyond could react. But if we were counting actions under the duress of encounter mode or a trap attacked them in that moment it might be relevant
Yeah, I mentioned the shield situation in the tactical entry that I wrote that follows the rules given by other comments here.
Interact [one action] Blue (Frequent)
Interact is the general-purpose action. It is used to draw a weapon, load a weapon with ammunition, open a door, close a door, grab an item, put an item into a pouch or scabbard, and many other mundane actions involving quick handling of objects. Donning clothing or armor would be Interact, except that that is so lengthy that it becomes a one-minute activity. Typically, Interact actions get ready for or clean up after a battle rather than fight the battle, so action economy calculations view them as inefficient. Thus, many class feats offer ways to combine an Interact action with another action in order to save an action, such as Running Reload which adds a subordinate (no-action-cost) Interact to reload a weapon after your character Strides, Steps, or Sneaks.Interacting with an item not already in hand requires a free hand. This can be inconvenient. For example, consider the difficulty of opening a door while holding a two-handed sword in a proper combat grip. Release the sword with one hand as a free action, Interact to Open the door with the newly free hand, Interact to Regrip the sword, and then Stride through the doorway. That takes a full turn. Holding a one-handed sword and shield is similar, because the character can Release the shield, rendering it useless for defense, but the shield is still strapped onto the arm so the character can Interact to Open the door and next Interact to Regrip the shield.
However, the alternative of wandering around with weapon sheathed to have a free hand in advance runs into the risk of a Reactive Strike. Interact actions have the manipulate trait that triggers the Reactive Strike reaction, so try to take all Interact actions, such as Interact to Draw a weapon, out of reach of any enemy with Reactive Strike to avoid extra damage. Beware that an Interact that is combined with another action via a feat still has the manipulate trait and still provokes a Reactive Strike.