Its pretty usable as a desktop. I recently switched from KDE/Plasma5 to LXDE, mostly to avoid rolling-release related churn. Eg, I don't want my UI to change everytime I update firefox.
I tried and failed to use it for Google Meet quite a while ago. The problem I had was something to do with the AMD USB chipset. I need to try it again.
What doesn't work natively is anything with DRM. There are workarounds, like running Linux chrome in a linux jail (think WSL), or running spotifyd for Spotify.
The NVIDIA drivers work fine for graphics applications.
Nevertheless NVIDIA CUDA is available only for Linux, so NVIDIA GPU compute applications do not work directly, but maybe only using the Linux compatibility layer (I have not tried that).
The nvidia drivers are a binary blob surrounded by a FreeBSD src-based shim layer. If you're running a -release branch, you just install the nvida driver pkg and you're done. If you run -current like I do (with no KBI guarantees) you re-build the nvidia port every time you update your OS.
All in all, the nvidia drivers "just work" and are very boring. I'll pay a premium for boring.
1) I use Zoom on Linux, and usually there's no sound until I go to the Zoom sound settings, press the "test sound" button, and then Output sound gets enabled. I have to do it for every meeting. Have you tried that?
2) Are you using Pulseaudio?
Nevertheless, a couple of years ago I have used FreeBSD also as a desktop for some time.
I have used XFCE, installed by compiling from sources, from FreeBSD ports, because that is what I use on Linux and I did not notice any problems.
The desktop experience depends a lot on what hardware you have, because of possible compatibility issues.
With an AMD Radeon GPU, I had some problems, I do not remember which. On the other hand, after installing an NVIDIA card and the NVIDIA FreeBSD driver, all worked perfectly.
My camera was a Logitech, I think a C920, and that worked OK, both video and audio on FreeBSD.