I've attempted to be rather conservative with claims that something
works, without detailed verification.
FreeBSD has a complete QEMU user-mode implementation in a branch right now. It's sufficiently advanced we build all our arm, arm64 and mips packages using it. What's in upstream QEMU is totally, totally broken. The work breaks things down so the common BSD could be shared. Starting from that base would be a huge leg up to getting things working.
I'm in the process of getting it upstream. FreeBSD's branch is a royal mess that has all the usual problem with a git branch that has lots of merges applied: it had become almost impossible to rebase. I've sorted most of that out, and am now sorting out collapsing down all the bug fixes and/or qemu API changes that happened over the years so each change in my branch is buildable. That should land this summer, maybe in time for 3.0, but maybe not.