I do not personally use GNOME or GNOME Boxes and I've never managed to get GNOME OS to so much as boot successfully in a hypervisor or on bare metal, and I've tried many times.
But I don't think it adopts all these fancy features yet.
It was a relatively recent change [1]. Try the latest Gnome OS nightly ISO in a VM -- you'll see that they've (largely) implemented the partition scheme suggested in ParticleOS: root on btrfs, two partitions for /usr backed by dm-verity, new /usr images delivered using "systemd-sysupdate".