No, they aren't since DNG (Digital Negative format) files are very large. Currently importing via USB to your computer is the only supported solution.
You can access the DNG files from file explorer using your PC. Simply double tap on your phone and browse to Photo > Camera Roll. The DNG files are stored there.
When using a Mac computer, you should download the latest version of Nokia Photo Transfer for Mac from here: http://is.gd/t5ZBHF. The newest version supports DNG files and will make it easy for you to download them to your computer.