Being a mobile this feature would take a lot of system resources.
You get the raw files into LR Desktop, sync the collection, and LR Desktop then sends smart previews to the cloud, which is what the iPad reads. Lightroom mobile is not designed to directly import raw files and then convert them into DNG.
Well I disagree ... new iPad Pro is more desktop than mobile, so I miss DNG conversion too - I'm moving to use iPad only. System resources is not a problem when iPad is on power supply - you could warn your users.
Please do not hold back on features for Lightroom for iOS - before you know it, Affinity have overtaken you (as they did with Photo/Photoshop) with their version of Lightroom ... and then I will reconsider my Adobe subscription.
I want Adobe to be king of both desktop and tablets - so please begin being serious on tablets! I can buy full version of Affinity Photo and Affinity Designer (when it comes out) for what a single month of Adobe CC cost me add a 2TB iCloud subscription and all I'm missing is a powerfull iPad Lightroom kinda app ... then I'm no longer an Adobe customer ... so please do not underestimate the power of tablets (or mobile devices as you call it).
I must agree with M O J O. The more I thought about the answer by Akash Sharma on Jul 12, 2017 8:21 AM
… the less I liked it.
My Nikon D7100 is set to store only RAW (.NEF) files. I import them into my iPad Pro via the Apple SD <-> Lightning USB3 adaptor (via Photos). I'm not sure if this import, via Photos, keeps the files in RAW format or converts them to JPEG. In either case, I was able to edit them via Lightroom mobile and that edit operation produced .NEF and their associated .XMP 'side-car' files. The results of the Lightroom mobile edits were sent to the Adobe creative cloud as .NEF / .XMP raw file pairs and appeared in Desktop Lightroom CC as RAW files. Thus, Lightroom Mobile produced RAW files as a result of it's edit operations.
If Lightroom mobile can create RAW files, there is no reason it does not have enough processing / memory capability to import RAW files directly and, optionally,e convert them to DNG format during import.
I agree with M O J O, "Please do not hold back on features for Lightroom for iOS".
Please add the ability to directly import RAW photos in Lightroom mobile, and optionally convert the to DNG during import.