The SmartThings V2 hub has a Bluetooth radio inside of it, but it has always been disabled and you cannot connect any Bluetooth devices to SmartThingd at this time.
They have not given any timeline for when this feature might be turned on. And it’s been about a year now.
Leviton Z wave switches will work with SmartThings. But not the Bluetooth models.
( I’m pretty sure what you were seeing in the SmartThings app is the Leviton Z wave model, DMX1 (zwave), not DDMX1 (Bluetooth). Unless you meant you were seeing it in the Leviton app.)
Hub v2 is also future-ready to support Bluetooth, but the Bluetooth radio is not currently activated.