Ok, I foxed it! I looked around in the log of which I mostly understood nothing, but then I came acress the section where the kernel/shstemd mounts the drives and the error it spits out. Googling it gave me an arch forum post with the identical problem. Windows didn’t shutdown correvtly the last time I used it and did something to the partition table. I’ll update my post wiy the solution.
Fastboot was never enabled to begin with :-/