you want to create a sensor using the statistics platform. It isn’t specific to z-wave, so there is likely a better channel. Statistics - Home Assistant
and
In the past some platforms, climate in particular I think, use attributes for non-primary functionality, and not as separate entities. Temp/humidity are the obvious exceptions. If you think it’s worthwhile that the operating mode/state should be a separate entity, then put the discussion in
devs_zwave , or submit a PR and maybe it will be accepted. I think there’s been movement towards that design lately, but I’m not the authoritative source. For example, fan mode was added as a separate entity. Otherwise, a template entity is the best approach today.