Gregory's Server@abcdw okay long shot: set explicit mount options in the file system mappings (SSD mounts). I had an issue with a newer SSD regarding those. I think it was related to space_cache.
Suggestion: "compress=zstd:1,ssd,discard=async,space_cache=v2,commit=60"
@blasfisq @dpflug
@JayLittle
Everything is unencrypted and booted correctly, root is mounted as well, but probably shepherd kills itself, by mounting a subvolume to /var (:
My bet that the problem is in /var being on a separate partition (subvolume), updated the configuration and will check it when it finishes to build.