Is there any way to transfer my locomotive roster from the DCS remote to my WiFi app like Lionel's Legacy system does?
Yes there is. The procedure for this is defined in Barry Broskowitz book. It boils down to exporting the information from your DCS remote to a file, changing the extension of the file and importing the file into the app. You'll want to reference pages 115 & 163 (1st edition) or page 119 (2nd edition).
I'd recommend getting a copy of the DCS WiFi Companion volume 2 from MTH: https://mthtrains.com/60-1411.
I'm planning to order both the DCS and WiFi Companions. Latest paper editions after the first of the month. I do have the Vol 1 companion which I know is outdated.