LUKS-encrypted root on ZFS does not take hours. I chose encryption when I installed the OS.
There is also the ZFSBootMenu part ...
If you have done this at least once - noted the commands, etc. - it will take shorter - but never shorter then FreeBSD 'Auto (ZFS)' option in the bsdinstall(8) installer where you just select the disk on which it needs to happen and hit [ENTER] key.
Reminder: I neither want, nor need, to check several different guides that cover only the encryption part.
In any case, I'll take additional advice; it's impossible to trust apparently authoritative statements from you.