How often per round can the ability of a pet/Artifact be used? Is there a differentiation between abilities whether they are once per round or “Passive” buffs and how to differentiate?

The rulebook clearly states that items and pets can only be activated once per turn. If it is a passive ability it is considered “always on” and does not need to be activated. If something does something like exploring or placing a token that is an activation. If it says “Ignore walls” then its passive.