What distro & version of Linux do you have installed? I've confirmed that if I switch the Canon RP to JPEG mode, it will capture images fine, however, capturing in RAW mode still fails, due to issues with linking to the updated LibRaw git snapshot and not being able to decode the CR3 format raw image with the olderLibRaw linked library. Since my original post, I've since found the "LIBRAW Latest for CR3" thread on this forum, which is talking about this issue.
Resurrecting this thread since I think I have the same issue. I have Canon EOS RP that also outputs CR3 files and have the same issue with LibRaw support to decode the image.
I've noticed that there is now a public GIT snapshot that now supports CR3 files: www.libraw.org/news/libraw-snapshot-201910
I believe have the latest PPA INDI Nightly Build installed.