update: I managed to get it working, look at the edit

It recognised the disks in an ASR array, but the type is “unknown” and it fails to assemble with “Undefined RAID type (null)[1] on asr_”. So I don’t think that worked sadly.
EDIT: The RAID card I had supported RAID 5 and dmraid doesn’t, that’s probably why it’s not working.

I could not find a --discover parameter, but I tried --assemble --scan and it couldn’t find a super block.
It feels a bit frustrating to have all the data here but no way to access it, maybe a tool will pop up at some point if I hoard the disk images.
Thanks for the suggestion though.

I like to have different naming schemes for different device classes.
Desktop computers: Greek gods
Laptops: Elements of the periodic table
Cloud servers: Norse gods
Home servers: Planets of the solar system
Raspberry Pis: Greek titans