How usable are the BSDs as a GUI daily driver? Like 99% of Linux applications work out of the box or more like 50%?
With new CVEs being discovered in ancient bedrock code on the daily, it seems prudent to switch to a NetBSD/OpenBSD/Qubes system for the next few years until some vulnerabilities might get smoothed over.
I use FreeBSD on all my machines for everything sinc about 11 years GUI is I3/X11/AMD-Card everything works, but please test it yourself, it's like with linux, you just know what's not/is working if you use it daily for all your edge-cases (maybe your scanner, maybe your barcode-scanner your Bluetooth-Stuff your wireless etcetc)
Overall i really love FreeBSD for everything computing (Pi/Laptop/Workstation/Servers).
And the community is great...wanna make a port/src-patch?...just send it to the bug-tracker, no rituals needed ;)
The cross build tooling, specifically around build.sh, makes the process of building a kernel + userland straight forward.
Use your best build hardware to build for your test hardware.
NetBSD 11 with Firefox 151 from pkgsrc on a custom CTWM is a usable daily driver for Emacs daemon mode GUI/TUI and console tmux simultaneous use. Remote in from a Windows or macOS desktop.
Please define what "Linux applications" is first.
Running OpenBSD as a daily driver but with no DE.
It has a working X11 with DRM from linux as base so everything graphical will work mostly fine. The issue is more around the OS and some subsystems. OpenBSD is still using the Giant Lock model, so SMP can be an issue. Linux has more independent subsystems so heavy processing is unlikely to impact usb audio (which is an issue I have with my oldish laptop). Another issue is the input subsystem (wscons framework) which is not as sophisticated as Linux Input subsystem. In general, linux subsystems are more sophisticated/complex than their OpenBSD counterpart, but the latter work well enough.
There are some linuxisms in some applications (the recent moves to wayland/systemd,...) but they're mostly easy to port.
Depends on what you need. Software compatibility is mostly good, as long as it doesn't have a dependency on systemd or some other Linux-specific feature. Driver support varies, but FreeBSD in particular is pretty decent there.
FreeBSD has a Linux compatibility feature that lets you run native Linux binaries. I've never used it so I can't say how good it is, though - all the stuff I use runs fine natively.
The major BSDs have decent package management and sizeable repositories, with the option to build software (and customize compile-time options) using the ports or pkgsrc systems. You can also rebuild and customize the kernel and base system (aka "make world") but that's strictly optional these days.
I seem to remember there was some GNOME stuff that had a hard systemd dependency and wouldn't run on the BSDs. That was a while back though and I don't run GNOME so I don't know whatever happened there or what the status is.