The raspberry Pi is considered a Tier II architecture on FreeBSD, so they'd just say it's a work-in-progress, and maybe not yet 100% "compatible" - to use your term.
Several other boards work, but some only in serial console mode. As far as the Pi goes, I have run Xorg successfully on the Pi2, but for the Pi3 I think there have been periods of time where it was not functioning. Like I said, it's a very fluid work-in-progress. I have used the Odroid C1 with FreeBSD, but it was a major hoop-jumping affair. I think some folks have used Beagle boards and Orange Pi boards as well, but I don't know how the Xorg works on those boards.
NetBSD works on a few additional boards, but that of course is not relevant to your question.
what are these cards