rsync.net offers ZFS send/receive and I’ve been using it for 5 years now, it’s pretty great. It’s not super expensive per GB, but they ask a minimum of 5TB if you want native ZFS support, which is $60/month.

You get access to a full FreeBSD VM which is very nice, because you can do things like metrics or a “pull” setup that pulls backups from your machines, so you’re more resilient against stuff like ransomware.