You may want to search up “FreeBSD Ports”. FreeBSD (TrueOS) are basically the kernel and standard utilities. Pretty much all user applications are in the Ports tree. I don’t recall the current count but Ports cover pretty much everything available on Linux.
XFCE, LXDE, a bunch of others are already available as ports. Project Trident will make it easier to choose something other than Lumina, but even now one can install the packages for them (if they are available in the repos) or build them from source. There is nothing preventing you from running what you want; huge difference between “what is in the default install” vs “what can you do”.
I’m a good example of this: I don’t run Lumina, KDE, Gnome, or any of the popular Desktop environments. I run WindowMaker as my window manager (I don’t like DEs, too bloated), like I’ve been doing for a long time. But it was not available in the default install, so all I did was install the packages.