I asked about that local-first, offline control, etc. when it was announced and the reply was that the team didn’t have information.
The official website is even more explicit about supporting “automations and controls” while offline. Even has a diagram where they show the locally connected devices and a broken cloud link like if it’s not needed, but the app to control the hub and the devices doesn’t appear and if it’s local-first it should .
I still hope that’s a feature, maybe not yet ready but coming in the future, would be a selling point and put SmartThings on par with other platforms with local controls and automations like Apple Home, Aqara (M3), IKEA (Dirigera), Home Assistant, Hubitat, etc.