You can open up the disks tool we include in Netrunner or check kde partitionmanager
This is what shows up in Disks.
GUID Partition Table = GPT so it is indeed gpt.
So I recommend creating a bios_boot partition with kde partition manager (if it supports it. It should appear under flags for a newly created partition). Otherwise I recommend installing gparted on the live disk and using it to create a bios_boot partition (I definitely has this flag option available)
Choose this bios boot partition as target for grub to install to.
So this is OK for the bios-grub thing?
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The installer crashed when I chose to install the grub menu inside of the reserved BIOS space
To be honest I am not sure as I never did this on my own. If no one else tried it before the only thing you can do is try it.