How are you getting the files off the camera?
I'd been considering using an Android tablet to backup files/view files when away from a desktop computer. When I transferred files using Camera Connect the files were converted to JPEG.
Canon told me the rename may not happen on all tablets, it depends on the processor. Why I don't know.
I can transfer them as CR3 files using a card reader successfully. I haven't found Android software which lets me copy files incrementally e.g. by date as I can do using Lightroom on a PC.
Lightroom Mobile on Android can copy CR3 files, but it saves them to a hidden folder and renames them.