I ran a shell out of a manipulated initrd.img and tried to load the module hv_storevsc.ko manually. This produced errors regarding missing vmbus symbols.
Afterwards I added the module hv_vmbus into the initrd.img which loaded perfectly. This triggered the module hv_storevsc.ko and the system booted.
Now just the module drivers/net/hyperv/hv_netvsc.ko is missing to use the native network adapters. Sadly this module is not found in 10full.tgz. It can be activated in the kernel config:
Device Drivers > Network device support
Microsoft Hyper-V virtual network driver