Simple clarifying question: does giving a creature the Stunned 1 condition thereby prevent their using a Reaction (such as an AoO) on the turn before the 1 Action is lost? I assume the text saying "You can’t act while stunned" means that you cannot take reactions while the condition persists (i.e. before you have lost your Action on your turn), but I am not 100% sure as terminology is quite precise in most conditions and that descriptive comment in the second sentence might be a general comment which is clarified in terms of the mechanical effect of losing Actions (which might be excluding Reactions, in that case), and not to be taken as a mechanical description on its own.
Sorry if I am overthinking or unnecessarily complicating what would be an otherwise quite straightforward rule.