Although there are different flavors of BSD, they are not like Linux distributions, they are complete operating systems, the user environment is programmed by the team of each flavor, it does not use third party tools, although it is true that you can share code, it is a different approach that offers a remarkable consistency and stability, since all components are designed and maintained by the same development team.

An interesting project for example is DragonFlyBSD, it is worth reading about all the features it has.