The Lightroom for mobile (Android) app supports the file formats listed here for importing and edits. Since the 5.3.1 release, due to some Android OS compliance requirement, the app allows import of those raw files that can be recognized by the Android OS as images.
When the Android OS extends support for all raw files, Lightroom will be able detect them for import. Until then, you can use one of the following workarounds to import raw files to Lightroom.
Open the photo in your Android device or long-press the photo from within your photo gallery. Tap the Share icon and select Add to Lr from the Share to Apps options. Your photo will be imported to Lightroom.
In case you're unable to find the Add to Lr option, use the Files app to locate your photo and then navigate to Add to Lr using the procedure mentioned above. If you do not have the Files app, download Files by Google.
Directly connect your DSLR or camera to your Android device and import the raw files. For more details, see Add or import photos and videos from a Camera connected in PTP mode.