You can currently add a zwave August lock, I have the 3rd gen pro model… but I will tell you from experience that it will eat your lock batteries alive. I got to the point of replacing batteries weekly before completely disconnecting ring. Not connected to ring, my lock has gone 2 months without low battery warning.
If ring could somehow figure out how to link to August locks via the August hub, that would work better because the hub uses Bluetooth to communicate to the lock which is why the battery lasts so long