I took a look using SideQuest, and SuperMedium stores files on Quest 2 in:
sdcard / Android / data/ com.Supermedium.Supermedium / files /comics
However, it does not, unfortunately, simply store .cbz and .cbr files. Instead the Windows desktop app (presumably) explodes them, changes file names, and adds a metadata file.
Specifically, it exploded my .cbr file into a directory with an apparently random number for a name.
- the image files were put into an 'images' folder.
- the images files were renamed, starting with "000", with no extension, and increasing numerically.
- a 'colors.json' file was put into a 'metadata' folder
It also put a 200 x 400 thumbnail of the cover into a 'thumbs' folder at the same level as the comic folder. The thumbnail had the same numeric name as the comic folder, with .jpg extension.
I tried a simple test. I exploded a .cbr file and put the jpg's into an images folder. I did not rename the images, not did I bother with metadata/colors.json. I created a 200x400 thumbnail. I put it onto my quest in the folder along with the other comics, fired up SuperMedium and ... nothing. It did not get picked up. Perhaps there's a database it's also using to keep track of what's on the headset ... who knows.
So it looks like attempting to reverse engineer all this is a hassle. Our best bet would be to hope the developer sees his way clear to supporting .cbz and .cbr files stored locally on the Quest. Then we wouldn't need the buggy and insecure Windows program. That would be great, because the comics reader itself is really, really nice. Too bad it's shackled to a dumpster fire.
You can also take a look at my post on the Proprietary library manager? No thanks! thread, which the developer never responded to.