Hey claplace,
thanks for your response.
You are right, the Firefly StationPC M2 by default ships with a Station OS (Android based) installation on the internal eMMC storage.
I took the prebuild ROC-RK3566-PC_EFI.img UEFI image and wrote it using balenaEtcher as stated in the guide:
In order to have the board booting in UEFI, the firmware has to be located in one of the supported boot devices. If the device (SD card, eMMC) are removable, the easiest way is to use dd, Etcher, etc. to write the appropriate .img file to the device.
After inserting the SD card into the device, it ist not booting automatically from it, I have to choose it in the bootloader.
Should it load differently?
Is there any difference from writing the .img file to the SD card between using etcher or dd under Linux?
I just flashed it again and don't see any difference in the boot process.
I can't find any official documentation on how to install ESXi ARM on this device. But it shows as supported, so someone must have been able to install it.