Oh the possibilities is endless....
You can get some humour by swearing at her, asking for a joke etc.
You can play multiple games, like rock paper scissors for instance.
You can play any artist's music in 'shuffle' mode using spotify free account (specific song request and playlists if you have premium)
You can stream radio stations, especially nice ones that has poor reception in your area.
You can turn lights and switch off (I have a colour wifi light bulb that cost about 200 bucks).
I also have some sonoff wifi switches which I hooked up to various devices e.g. my pc monitor to turn it off by voice when I don't want to get up.
Ask the weather, ask chances of rain in your area, etc etc etc
You can even tell her to remember your favorite number and when you ask her again she will tell you.
Same with things like e.g. 'What is my brother's name' - if you tell her she will remember and all of this info get saved in your google account for future use.
Also, multiple people in the house can install the google home app and let her record their voice print - this means I can say: 'Ok google, where is my phone' and it will ring my phone even though it might be on silent.
But if my brother gives the same command, his phone will ring.
Then there is of course 'routines' - if I tell her 'Ok google, good morning' she will tell me the weather and read the latest news as well as tell me about my daily schedule if I put it in the google calendar app.
These routines you can edit in the google home app, add things like turn lights on and off etc
The default 'good night' routine would for instance ask you what time you want the alarm set and then play some sleeping music (crickets lol).
Possibilities are endless and the AI get improved in the cloud daily, so the speaker gets new functionality on a regular basis.
If you tell her 'Ok, google, I hate you' she would even offer to record your voice in order to give feedback to the google team on how they can improve.
Basically ANY THING you can think of asking you can try and see the response, also stuff like conversions e.g. inches to cm, anything you can google you can ask via voice.