To clarify all data that is transferred from Linux ZFS to FreeBSD based systems or visa versa is copied using restic or rsync.
I only use ZFS replication when doing Linux to Linux transfers and when that happens they are running the exact same operating system and version of OpenZFS.
Eh, especially if you're just using Linux and FreeBSD (doubly so now that they're both using openzfs) it's easy enough to keep pool features compatible. Obviously you need to either pin to a compatible feature level or avoid upgrading the pool, but I don't think it's terribly hard.
This was before freebsd used openzfs, maybe easier now. But my point still stands, you are off the beaten track at a time when you want to minimize risks.
I had tons of issues getting it to work with versions too far apart, which tainted my feel for that approach.
There is an argument to be made for dumb file copying even when you have access to fancy features.