[Libguestfs] client-side LUKs + NBD over internet?

Hi Richard et. al, I was attempting to ask this question via a comment on this post (https://rwmj.wordpress.com/2022/05/14/nbdkit-now-supports-luks-encryption/) on your wordpress site, but it was giving me some trouble, so I will ask it here: I hope this is not too naive of a question, but is nbdkit (or even just nbd in general) a good fit for mounting and using a LUKs encrypted block device over the internet? Specifically, the client would encrypt the block device using luks and thereby keep the luks secret key local like you did in your blog post. I have done some rudimentary tests with nbd-client but have been unable to achieve speeds faster than approximately 1.4 MB/sec. However, doing the same thing on my local network gave me closer to 50 MB/sec. The latter seems usable, but the former seems not, and I would like to better understand if/how nbd can be used over the internet. Thank you in advance for your reply.