I have just got my hands on an RCD510 DAB. The RCD radio is the non-nav radio. The RNS radio has nav, don't know if you can get a DAB version of it.
Been spending a lotta time researching what aerials, connectors, etc are necessary. You can buy all VW equipment but it's quite expensive.
VW offer a long cable (front to back of car) and an aerial that hides behind the plastic of your bootlid. This option is £100+.
Other options are a run-of-the-mill front windscreen aerial that will normally have a female SMB connector. The jack at the back of the RCD510 is a FAKRA Type A. So you'd need a FAKRA Type A (or Z which is universal) to SMB adaptor then the window aerial. Adaptor ~£5, aerial ~£20.
Hope this helps.