See How to override folder with backup - #2 by gurkan and Restore only subtree of snapshot via <hash>:<subtree> syntax · Issue #3871 · restic/restic · GitHub which would propose the syntax restic ls <snapshots_id_here>:/home.
And feel free to try out rustic (I’m the author) which does already implement this syntax for ls, restore and diff.
Regarding the original question about ls --depth: This is not yet implemented, but if you open an issue, maybe it gets implemented…