I recently came across Spectrum. I myself use Qubes OS quite a lot, and
I also find Spectrum really interesting. (Though I'm not very technical,
so I'll have to wait for development to be in another stage for me to
try it.)
On the mailing list, I saw an article about FlexOS, which has some
similar goals, though it seems to be in very early stages. I thought
PlagueOS might be of interest to people here as well. Like Spectrum, it
has better hardware compatibility and performance compared to Qubes OS.
They use Void OS as hypervisor(looks like standard KVM compared to a
more secure Rust alternative) and a lot of hardening. It already has an
ISO image available and a graphical desktop environment, so it can
already be used by people with not much technical skills.
discuss(a)spectrum-os.org