Apologies for not replying in German, but here is some info that might help someone else do it.
The following thread is directly related to the TUXEDO Gemini 17 Gen 1 (no answers yet):
There are a few TUXEDO laptops in the Hardware Compatibility List (HCL)—TUXEDO section in the HCL—but not the Gemini 17 as far as I can tell.