Another proof comes from FreeBSD comfortably booting on QEMU, which uses coreboot+SeaBios by default.
Personally, I've installed FreeBSD on a friend's Chromebook, with Coreboot+SeaBios, replacing the stock Chrome's proprietary payload. In this regard, an interesting page to look up is Chromebook FreeBSD.
FreeBSD should also have no problem booting on TianoCore as well; however, I still have to test it. Meanwhile, give a look at freebsd/uefi-edk2 on github
Regarding LibreBoot, I do not know much about it,but this message on freebsd-current mailing list is disheartening
However, this official tutorial states the contrary: libreboot should be viable on FreeBSD, as it seems LibreBoot supports GRUB2 or depthcharge (Chromebooks proprietary payload) as payloads. This also implies that FreeBSD should boot on depthcharge either, without having to wipe the stock firmware out