I don’t have direct experience, but when I looked into it my takeaway that NBD was unable to reliably deal with network interruptions as well as iscsi.

https://forums.gentoo.org/viewtopic.php?p=4895771&sid=f9b7ac...

https://github.com/NetworkBlockDevice/nbd/issues/93

Whether that’s the case with the latest version, I don’t know, but it’s something you might test if you choose to try it.