From Odroid HC2 with 2TB disk to an Odroid H3 transition

I’m in the process of setting up a new nextcloudpi instance on an Ordoid H3 system. I still have a HC2 nextcloudpi with a datadisk=2TB HDD (btrfs) that I would like to use in the new system. My datadisk contains the ncdata dir and backups.

The idea is to use the NCP lxd image to set things up following this guide.

I struggle at the point where I have (according to the guide) to create the storage.
My partition (which is the whole datadisk HDD) should be used and the suggested command is
lxc storage create ncp btrfs source=/mnt/your-disk. <---- Does this wipe out the data on the disk?

(I run this command already but interrupted it after it took >1minute because I was getting unsure what it does)

Any ideas on how to proceed? (I have also copies of my snapshots on another disk but I am not quite sure it contains everything I need)