ZFS on Linux denied access when accessing child dataset on NFS

Solution 1:

access denied on the child from the parent mount

sounds very much like what is explained in https://blog.programster.org/sharing-zfs-datasets-via-nfs (emphasis from original):

it is very easy to split your "pool" into as many datasets as you like. Each dataset is treated like its own filesystem, with its own rules and settings, which means with regards to sharing over NFS, that you can share more securely as client's will not be able to reach out of the bounds of that dataset/filesystem that you decided to share.

An important thing to bear in mind is that you will need to run the steps below for sharing on every pool/dataset that you wish to share, no matter the hierarchy. For example, if you have a dataset that is the parent of another, you would still have to set up sharing on that child if you wanted it to be shared, even if you have already set up sharing on the parent.

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