Zfs is the same cosebase that runs on linux (freebsd people literally dropped their implementation and imported openzfs into their source tree). It’s not merged in linux purely for license incompatibility (cddl vs gpl, iirc?)

For the other stuff (aslr, pf, dtrace etc) linux has either equivalent or better alternatives (eg: perf/ebpf, iptables/nftables, kvm) etc.

Regarding btrfs… most linux distro ship it and some (eg: fedora) use that as default fs.

Zfs is more intuitive and more ergonomic in my opinion, but i might switch to btrfs anyway if anything so I don’t have to worry about updating the kernel.

> instead of porting XFS or BTRFS the BSD devs chose to keep developing a fork of Oracle/Sun's commercial product.

Again, not true and actually the exact opposite: since openzfs is cddl-licensed, oracle cannot use that in solaris.