Out of tree still means not part of kernel.org upstream. You’re imagining a tighter ZFS integration than is actually there in Ubuntu simply because of misunderstanding used terminology.
What are you trying to say? They all use ZFS on Linux (today named OpenZFS). Gentoo and Ubuntu aren’t different in that regard. Ubuntu’s QA verifiably sucks, though.
Out of tree still means not part of kernel.org upstream. You’re imagining a tighter ZFS integration than is actually there in Ubuntu simply because of misunderstanding used terminology.
https://didrocks.fr/2019/08/06/ubuntu-zfs-support-in-19.10-introduction/
What are you trying to say? They all use ZFS on Linux (today named OpenZFS). Gentoo and Ubuntu aren’t different in that regard. Ubuntu’s QA verifiably sucks, though.