I have used FreeBSD for a over a decade now. ZFS was the new cool thing I feel in love with.
Today its a different story. FreeBSD is cool, and you will learn more about Linux by learning FreeBSD and it works really well.
However I am currently moving my last system away from FreeBSD. It is just that, Linux/Centos is better, and easier to maintain. Especially third-party packages. There are other things like Linux has support for NVMe-oF which I use together with ZFS on Linux. Applications, especially databases has often 1x-2x better performance. Virtualization is better and more performant. Better NUMA.
But Linux is not made for long running systems, you make a image and throw it away if it's not booting anymore, it's like smartphones and ioT devices, if they stop booting throw them away, linux and it's filesystems are good enough for that ;)
Void Linux is probably as close as you'll get to that. OpenZFS is supported across every packaged kernel, and it has native packages for ZFSBootMenu. You can't just click-through to a root-on-ZFS setup like you can with FreeBSD - but Voids' installer is rarely used to begin with. Boot environments aren't as deeply integrated into Void as they are into FreeBSD. That's more a lack of desire/will than a technical matter.
Edit: I forgot about Project Trident. They migrated away from FreeBSD to Void Linux with ZFSBootMenu. They did actually support root-on-ZFS through their installer. They gave up after about 18 months, they weren't able to differentiate enough after they stopped being based on FreeBSD.
Thanks for at least a partial solution. Installation can be scripted.
I remember the disappointment after PC-BSD died and Project Trident invested their 'time' into Void Linux instead of FreeBSD ... then I thought that it actually my be a good move - so finally some Linux would have some ZFS and ZFS Boot Environments love - especially as these people used ZFS Boot Environments on FreeBSD earlier ... and then it all died.
A lot of potential killed/lost there. First - PC-BSD introduced PBI packages - something that is today known on Linux as SNAP for example - some application packed together with libraries and dependencies in one 'package' - then for some reason they killed this idea - while Linux 'reinvented' it as SNAP (and others) and 'The World' was (and sometimes still) is fascinated by it. Sick. Same with Docker that was introduced in 2013. The so called 'World' went crazy with 'containers everywhere' ideology while FreeBSD Jails were available 13 years later since 2000. Sometimes I just got the idea that Linux people do not see any other innovations other then that happened with Linux system. Like FreeBSD Jails or Solaris Zones or IBM WPARs or HP-UX nPars never existed ...
Today its a different story. FreeBSD is cool, and you will learn more about Linux by learning FreeBSD and it works really well.
However I am currently moving my last system away from FreeBSD. It is just that, Linux/Centos is better, and easier to maintain. Especially third-party packages. There are other things like Linux has support for NVMe-oF which I use together with ZFS on Linux. Applications, especially databases has often 1x-2x better performance. Virtualization is better and more performant. Better NUMA.