I would love to have an open source microkernel OS that works as well as Linux on modern hardware even if the API wasn't stable. I am making assumptions that you could have ZFS and secure boot at the same time without jumping through hoops, containerization without needing fictitious UIDs for every user, and other things of that nature. The monolithic kernel is very frustrating with some things.
The hoops that ZFS has to go through are twofold: licensing and unstable internal API. I don't see how a microkernel (on its own) fixes either of those things.