Type 1 hypervisors run on bare metal, and motherboard vendors provide software that allows bios to be flashed from a running OS. Can I flash a motherboard bios from within a running guest OS if flashing tools are available for it?
Well no. Type one hypervisors run on bare metal, as opposed to on top of another OS. The guest OS is usually not aware of the underlying hardware except when exposed by something like IOMMU - not all motherboards use it, and I'm not sure if IOMMU lets you access the bios - its more typically used for video cards.