I’m pretty sure it’s doable but I don’t if it would be considered easy. Assuming you have an Android phone you’re going to need Tasker+SharpTools+Autovoice+Autocast (pretty sure you’ll need the paid versions).
I’m far from an expert in Tasker so someone else might chime in with a better way or another way completely.
You would need one Tasker profile set up to have SharpTools monitor the contact sensor and have Tasker set a variable every time it opens. Then you would need a separate Tasker profile using Autovoice which would allow you to ask your Home “When was the litter box opened last” or whatever phrase you want. The associated task could pull the variable and using Autocast announce the variable over your Home.
There are two ways to do this. The first is using the “cast” method, where a middleman server casts an MP3 file to you google home. This would allow you to send a message to a specific Google Home (or home mini) speaker).
And the second is using assistant relay. I just got this working and it’s a bit more complicated. This uses the google home broadcast feature. It sends a message to all google home’s on your account but it allows any music you are casting to the device to continue after the interruption and also allows for some fun presets (like the rooster for the wakeup broadcast).
You easiest thing to do then is to use WebCore to send the message either via the speaker using “Speak” action or in the case of assistant relay, using a POST message in JSON format.