First things first, what country are you in?
Next, is this for a mains powered switch or a battery powered switch?
If it’s a mains power switch in the US, there are many. Pretty much every Z wave manufacturer for the US now makes a rocker style. You can just start with the ones on the official compatibility list:
Leviton, Zooz, GE, Enerwave, and Honeywell are all options:
If you are looking for something that doesn’t control the load, both Zooz and Inovelli make models that can be configured for that option. They are still wired into the Main’s, but all they do when you press them is send a message to the hub.
If instead by “button“ you meant “battery powered,“ you still have a couple of options in the US.
The Ecolink smart switch cover is intended to be placed over an existing rocker and physically move it, but you can place it anywhere you want and it will work fine just for sending messages to the hub.
The Eaton Cooper aspire “any place“ which doesn’t look exactly like a rocker, but it does look like a regular light switch and is very popular:
If I’m not understanding what you’re asking for, or if you are in a country other than the US or Canada, let us know.