Yeah and it’s awesome. I have it making backup snapshots automatically and I copied the steamos-readonly script from valve to automatically lock everything except my home/root/var/opt etc (I realize you can remount ext4 as ro too, but still btrfs handles this well).
I recently swapped the contents of two drives of different sizes (one was a server and the other was a PC) and btrfs made the filesystem resize and expansion parts easy.
On my PC and all my home servers I keep my root partition at 10GB and haven’t had any issues (although I keep everything that isn’t hardware related or a system utility in home).
On my PC I crammed arch, all of KDE (+extra KDE utilities), and some other system stuff like LACT and distrobox in the 10GB root partition and run almost everything else as a flatpak installed to home.
On my servers I do the same thing but all my services are in podman containers in /opt.
Having all the software needed to make the machine work be isolated from my custom home junk makes me feel better, and I like that I can mount root as read-only to make it immutable