eOS (GSI-version) on Doogee V20 Pro does not start

[Ralph_Stgt]

I would like to have eOS on my Doogee V20 Pro.
As there is no dedicated version yet, I was hoping to be able to flash the GSI-version.
By using treble, I found the right “system.img” and I could also flash it, but after flashing, eOS does not start. It goes immediately into the fastboot mode.
Do I need to flash further files? Or change some settings by any command of fastboot?
Maybe I have a similar trouble as described here:

Phone boots straight into Fastboot after flashing GSI

I’m trying to flash an /e/ GSI onto a Xiaomi Redmi 8A (olivelite) device. My first attempts lead to a broken device that boots straight into fastboot every time. Flashing system.img worked without an error message. I did skip the Remove dm verity step that is outlined in the official guide in the hope that it would work anyway, but, well, it didn’t. My problem with this is, it says to do it either using TWRP, which does not seem to exist for that particular device model, or to do so by “extra…

but I have not yet the original Doogee stock ROM files. Doogee promised to send them to me soon, so hopefully I can try to re-flash “boot.img” and make the “–disable-verity”-step.

Regain your privacy! Adopt /e/OS the unGoogled mobile OS and online services

[Xxpsilon]

If your Doogee is running stock Android 12 or A13 - /e/OS-Q GSI (Andrroid 10) may not work.

Only use GSI images with an Android version that is higher than or equal to the Android version running on your device.

The files boot.img and vbmeta.img can be dumped on the running system, for example with MTKClent via python (Linux Ubuntu, ArchLinux, Windows).

[Ralph_Stgt]

I have received the original firmware from Doogee and could re-flash my phone to bring it back to live.
Now I saw that Doogee calls their system file (the big one with 2+ GB) not “system.img” but “super.img”.
Flashing a generic android 12 did in no way start yet, so I wonder if there is a special “boot.img” or “vbmeta.img” to call this android 12 “system.img” instead of the no more flashed “super.img”?