It depends on the specific brand and model. There are a few older zwave models that will work without a neutral, but these are only compatible with incandescent bulbs, not with dumb LED bulbs, so the models were discontinued in favor of the ones that do require a neutral. Cooper does still make one of these, but again, only for use with incandescencts.
You do have two other options.
- Most models of Lutron Caseta switches do not require a neutral and there is an official smartthings/Lutron integration now though it does require that you also have the Lutron smartBridge ( One smartbridge for each 40 switches). You can get a starter kit which has one dimmer switch, the smartbridge, and one pico remote which can be used as the auxiliary switch for a three-way.
These are nice switches, and they are what we use at my house.
- The new Aeotec nano dimmer switch is an in wall micro which is supposed to be able to work without a neutral, I’m a little skeptical because normally, with the exception of Lutron who hold a bunch of patents, that would mean it could only work with incandescents in that configuration. But maybe they’ve worked something out.
@TheSmartestHouse is carrying these, so they may know more
Assuming the nano does work, those would be your two best options, although if you pick the nano you’re going to have to figure out what you need for the add on switch to go with it.
Updated to correct I just realized I misunderstood the first post, I thought there was no neutral at the master position. My bad. But if you do have neutral at the master position, you can just use the master as a standalone switch, it doesn’t have to be connected to an add on if that’s what you’re asking.
Then, as @navat604 said, you just need to find a way to get a neutral wire to the auxiliary position so you can get that one working as well.