Could you elaborate on how this is particularly more secure than Qubes OS? I don’t think seL4 will be very suitable for this because of its likely very lacking hardware support (unless there’s an army of developers making networking and graphics drivers for seL4 that I don’t know about). Xen + a Linux dom0 seems like it probably gives similar levels of security to this.
Genode looks really cool, I didn’t know about it before. (Edit: Heh, looks like they’re using separate Linux VMs as both hardware and an application compatibility layers. Clever.)