Chess.com does support play with a DGT smart board! You will need to enable a setting in Live Chess before you can use it.
First, hover over 'Play' in the left menu, and click 'Play'
Next, click on the settings gear icon near the upper right corner of the board:
Then, be sure you have selected the 'Board' tab in the next menu, and scroll to the very bottom of the options. There you will see the switch to enable the DGT board!
Flip the switch to the right of the DGT Smart Board option, and then click 'Save'
You will now be able to control your games using your DGT smart board!
Currently Chess.com will support the following boards:
DGT Pegasus
Millennium King Performance (requires separate ChessLink module)
MIllennium Exclusive (requires separate ChessLink module)
Millennium Supreme Tournament (requires separate ChessLink module)
Millennium E-One board