None of the BSDs provide the requisite long term ABI compatibility; or rather, the only long-term ABI compatibility offered by FreeBSD is its (incomplete) implementation of the stable Linux ABI.

https://wiki.freebsd.org/Linuxulator

https://wiki.freebsd.org/VendorInformation

Major releases are cut from the main development trunk every 24 month ... No compatibility for API and ABI is guaranteed from one to the next major release, though an effort is made to make the upgrade process and source code changes as untroubled as possible.