Continuation of my adventure with sudo:
I wanted to check the first part of @tangmaomao16’s question, and since I can’t edit fstab on the server where I am using the containers, I installed lxd locally and mapped the situation from the server. Indeed, adding dev and suid fixes the situation. Unfortunately, as I mentioned before, I cannot edit fstab at the destination. So I have a question:
Is there a way I can change / overwrite mount options for the storage pool. I saw in another discussion (https://discuss.linuxcontainers.org/t/storage-pool-default-mount-options) that there is such a possibility for btrfs, is there such a thing for dir?