ZFS Is it possible to expand raidz2 with a smaller number of larger disks?

I've been doing some Googling on the subject and I've seen that raidz expansion is in the works but I'm not totally clear on whether it has landed already with 13.1, or if we're still waiting. I'm also not sure if it's even applicable to my situation.

What I'm trying to do is take an existing array of 8x 8TB disks on FreeBSD which are in raidz2, and replace them with a set of 6x 16TB disks in raidz2. This pool is the same one holding the OS and everything else.

Is this possible without offloading the data first and without reinstalling the OS?
 
Do the disks only contain some data(database) or do they contain the operating system ?
Do they contain directory /boot or do they contain /usr/local which will be a different situation.
 
The disks contain everything, including /boot (though I only now realize it looks like it is not on the ZFS pool which I imagine may be problematic for this).
 
I guess you already appreciate why it's generally better, with large ZFS servers, if the zroot pool (along with the boot stuff, and swap) is on separate media.

SSDs don't need a lot of cooling, and my zroot used to be an SSD mirror pair, physically attached to the server chassis (and held aloof from it) with velcro.

How many disks will attach simultaneously to your server? I'm guessing less than 14, meaning that a simple zfs-send(8) is not an option.

I don't believe that RAID-Z Expansion is currently available in FreeBSD 13.1-RELEASE, and I think I would have noticed an announcement,

However, the article published by the FreeBSD Foundation says Q3 2022, so any time now.

Hopefully, somebody with developer insight will clarify.
 
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