Raw Disk mount options

If i add a partition to my container via
lxc confige device add c1 disk1 disk source=/dev/sdb1 path=/mnt
lxc confige device add c1 disk1 unix-block source=/dev/sdb1 path=/mnt
Is there any way to use mount options like compress=zstd:15 for btrfs partitions?
I tried with to do lxc config device set c1 disk1 btrfs.mount_options and block.mount_options="compress:zstd" but neither works.
Error: Invalid devices: Device validation failed "disk1": Invalid device option "btrfs.mount_options"
Is this even possible or am I just using the wrong commands? I don’t want a shared folder with the host.

That’s what raw.mount.options is for.
Note that compress=zstd is likely a more appropriate value. I don’t know of filesystems that use : as key/value delimiter for mount options.

Thank you, now it’s working. The : is not a delimiter, I meant the compress=algorithm:compress_level btrfs mount option.