The problem is a bit different than described. There is no "extra" NVMe on AWS instances.

When you use an AWS Instance that has local NVMe disks - or what they refer to as instance store volumes - there will also be a volume that shows up as NVMe but however isn't. This is the root/boot volume which is in fact an EBS volume, however when you run lsblk, it will show up as if it is an NVMe.

Some more information here: https://docs.aws.amazon.com/ebs/latest/userguide/nvme-ebs-volumes.html

This is even the fact when you add additional EBS volumes to the disk, they show up as NVMe.
Here's an example of an i4i.large where I set the root volume (EBS) to 30GB and also attached an EBS volume of 40GB.

nvme1n1      259:0    0    30G  0 disk 
├─nvme1n1p1  259:3    0  29.9G  0 part /
├─nvme1n1p14 259:4    0     4M  0 part 
└─nvme1n1p15 259:5    0   106M  0 part /boot/efi
nvme2n1      259:1    0 435.9G  0 disk 
nvme0n1      259:2    0    40G  0 disk 

There is a way to filter out which are really the NVMe, the shown serial using lsblk -o +SERIAL with EBS volumes shows the volume id, as explained here: https://docs.aws.amazon.com/ebs/latest/userguide/identify-nvme-ebs-device.html.

Either way, it would be a good start to indeed not use any "NVMe" that are not in use. I don't see an immediate way to filter it out using the nvme command, so perphaps lsblk is the way to go.