Update: I have been doing image development in darktable via RAW files from the beginning. However, converting OM-1 ORF files to DNG is unfortunately not the solution I had hoped for. Was wondering about the blurriness of my shots and initially attributed that to me and my quality of experimental photography with manual old glass. However, when comparing files, the JPG straight out of the camera shows a much more detailed and better image than the DNG after development, which leaves me a bit puzzled. So I currently use the JPG for image development. This limits a bit, but still delivers good results.
So I continue to wait patiently for the OM-1 integration and hope that this will be possible with the 4.0.1 release for Windows that I am eagerly awaiting.
Best regards to the developers: hopefully you have enough time and possibilities to do that.