I believe it would be less “error prone” if you use incus/lxd file pull and file push to manage files inside one or more containers.
In your example scenario, not mounting the file from the host ensures the nginx service inside containers to operate continuously even if something interferes with the host /mnt/NVME1/data/nginx.conf file (like deleting it or changing its content to an invalid one).
It will work fine, the main catch though is that most editors don’t actually modify a file, instead they modify a copy and then delete+rename.
This means that if you now edit the file, either in the container or on the host, the change will not be reflected as the mount will remain tied to the old copy of the file.