“Hey—have you got some time to chat about Fizz today? [Optional second sentence indicating level of urgency in your part]”
If they don’t get back immediately, you can safely assume “right now” is not a time they have. If they actually don’t know shit about Fizz and you need to bug someone else, they can communicate that when convenient without needing you at your keyboard when they do it, because at least they know WTF you want to chat about.
There is no benefit to just “hello.”