An article has been added to the community – created wiki listing devices that will work with both HomeKit and SmartThings. Feel free to add more as they become available.
@JDRoberts You can add Sonos to the list.
So can you; it’s a wiki.
Do we know if it will still work with SmartThings when is configured to work with HomeKit? Logitech Harmony’s Pop buttons, for example, get configured so they will work with either HomeKit or smartthings, but the same button can’t work simultaneously with both.
Also note that it’s only the model three, Gen one and two don’t enough memory for the upgrade.