During its Unpacked event this morning as part of CES, Samsung confirmed that Android Auto would gain SmartThings integration in the near future. Based on the limited amount of information Samsung has given out thus far, it does seem that you will need a Galaxy S21 if you want to use the upcoming feature.
That being said, there is always a possibility that Samsung could extend that compatibility to its other phones eventually. Like the Galaxy S20 and Galaxy Note 20 series. For now though it sounds like this is a Galaxy S21 exclusive feature.
Use your Android Auto in-car dashboard to control your SmartThings home devices
Smart Home appliances can already be controlled from virtually anywhere. But the integration of SmartThings with Android Auto makes this process a whole lot simpler. Not to mention safer.
Once this feature rolls out, you'll be able to to tap on the dashboard and launch the SmartThings app. From there you can hit a button called Coming Home that will start controlling certain smart home devices.
You can set this up to adjust the temperature on your Nest thermostat. As well as start your Samsung washers and dryers, robot vacuums, and smart lights. By doing all this from Android Auto, you can safely complete a few tasks that you may have had to otherwise do once you walked in the door.
Now you can come home to those tasks already done. Which gives you more time to relax.
There will also be a button for Going Out that will initiate tasks you would normally want done while you're gone. Like turning off lights, turning he temperature down, or locking your doors and windows.
Samsung hasn't said when the feature will launch
While this is a feature that will work with the Galaxy S21, which you can already pre-order starting today, the integration is probably not something that is going to be live right from the start.
Samsung didn't announce availability of the SmartThings integration during the event. So it's likely that it still may have some things to put the finishing touches on before it rolls things out.
This also shouldn't be an issue for users. As the Galaxy S21 series devices aren't available yet either. You can pre-order them, but they aren't officially launching until the end of this month. So even if the Android Auto integration was available right now you wouldn't be able to use it anyway.