Ok, it doesn't integrate with the system at all. This provides a library to access the device. I.e. it can only be used by a single consumer, that consumer doe

Ok, it doesn't integrate with the system at all. This provides a library to access the device. I.e. it can only be used by a single consumer, that consumer doesn't get nice things like ther kernel's file systems or device mapper (raid/crypt/verity...) features. This can be fine, e.g. when the consumer is a database that just needs a block device, or something like ceph/minio etc. that provides the storage api to its consumers. It'd have to use something like NBD (~fuse for block devices) to actually integrate and then my previous post describes some of the downsides to that setup.