There are lots of button devices that work with Hubitat, but specifying Z-Wave only is going to limit you a bit. You can see a list of supported buttons in the official list or (with some notes on capabilities) here: Hubitat Elevation supported button controller capabilities matrix
In fact, you can have exactly what you want above with a Lutron Pico remote (the 5-button one is usually cheaper, but there's a 2-button one that looks exactly like that, and despite the engraving you can mount it horizontally if you want). Unfortunately, that requires (at least) the Lutron Smart Bridge Pro, which would make this over a $100 endeavor for just one button. But if you want enough, the Picos are cheap enough it could be worth it.
Assuming that's a no-go, I'd look at the other devices in the list and see if any look like what you want. The Aeon Wallmote is Z-Wave like you want but isn't as small as some buttons, but not ugly. The Hank went out of stock before I could try it (and I don't want it anymore), but it looks like it would be good. If you're willing to consider Zigbee, the SmartThings button is tiny and cheap and would be a good choice, but you'd either need two or have to use different actions (tap vs double tap, etc.).
As hinted at above, you can also use most Z-Wave "scene"-capable switches as just scene switches if you want. Many support disabling the relay, so even a single tap up or down will just register as a button press and nothing more. Even with ones that don't, wiring line and load together or leaving off load (depending if the switch or you need one) is usually a hardwired way to do the same.
