Is this a radon detector?

Good morning,

Moderators, if this is the wrong forum, feel free to move.

Yesterday, we had a real estate agent walk through our garden unit condo and she stated she was surprised to find no radon detector. I believe we have one (see pics below), but I’m not sure if it is a radon detector or not. If it is, how do I check if it’s working?

Thank you!

That is an alarm system siren.

Why was your agent surprised to find no radon detector?