Rainer Weikusat:
...
> I'm willing to put work into this although this would only proceed
> slowly as this would amount to just a few hours each Sunday.

If you want to spend time on this we could assemle a small group
handling this in devuan.

The easiest solution to this is using a kernel with needed drivers
compiled in. My suggestion is to add:

CONFIG_SATA_AHCI=y
CONFIG_MD_RAID1=y
CONFIG_EXT4_FS=y

and using busybox init and mount.

Regards,
/Karl Hammar