Years ago, there was a project combining Debian with the kernel from FreeBSD. That never made sense to me and the project seems to have died meanwhile. More sensible, IMHO, might be to bolt the FreeBSD user space unto the Linux kernel. That way one would get fairly broad and current hardware support and could still enjoy a classic Unix look&feel and stable ABI.
A lot of BSD utilities that are not POSIX has really close interaction with the kernel. OpenBSD’s *ctl binaries are often the user-facing part of some OS subsystem. Linux subsystem often expose a very complex internal that you need to use some other project to tame down