Currently, you can transfer the game to another device via Facebook, Game Center (iOS), Sign in with Apple, and Google Play Games (Android). To transfer the game to another device, link your account on your previous device to any of the services listed above to save the data.

How to link to the services:
Linking to Facebook and Sign in with Apple is done through the game settings.
Linking to Game Center (iOS) is done through your device settings.
Linking to Google Play Games (Android) is done through a special icon in the game. This icon is located to the left of the energy icon on the Darkwood map.

After that, log in to the selected service on your new device. The game will offer to restore your saved data.