I made a single Debian partition using the new flashing tool. The tool doesn't specifically allow it, but if you choose Sailfish it does. So I did this:
1. I chose Sailfish, then downloaded the scatter file.
2. I downloaded the Debian image
3. I copied the debian image and the Sailfish scatter file into the Gemini base image folder as instructed
4. I then ran the Firmware flashing tool and loaded the Sailfish scatter file
But at that point you'll see a couple of the options aren't ticked in the flash tool (from memory boot, boot2 and boot3). Because these are pointing to the sailfish image (which doesn't exist). So you just need to
5. Open the scatter file in a text editor (if you're using Windows I'd recommend Notepad++ or somethign and make sure the file Line ending is set to Unix (LF). Notepad I think uses Windows Line Ending so the file will probably become corrupted)
6. Search for sailfishos_boot.img and replace it with debian_boot.img then save the file
7. Reload it in the Flash Tool and all should be ticked.
Let me know if you have any trouble and I"ll send you my scatter file. As long as you only want a single partition and you have the X27 sim version, I think it should work.
