The GPU acceleration for macOS guests announcement for Parallels 16 is HUGE for all of us. Is this only in Big Sur guests? We all hope NOT NOT NOT NOT NOT!!!!!! We very much need Metal acceleration in macOS 10.14 and 10.13 or even below. This is super important for many of us who rely on older systems for 32 bit support and other functionality.
Yes, it is only Big Sur guests that get 3D video acceleration per Tech Support below: Yes they said "with Big Sur as the host operating system the Parallels Desktop can support 3D acceleration." but my application worked in the Big Sur Beta guest running on the Mojave host. It didn't work in Mojave nor Catalina guest VMs.