Walkthrough:

Host: AMD Ryzen 7 2700X, Windows 10 1909, 16GB RAM

Guest: VirtualBox 6.0.18, 2 CPU, 4 GB RAM, 128MB VRAM, VBoxSVGA Graphics Controller w/ 3D Accel on, 2 Virtual Displays.

Guest OS: https://manjaro.org/downloads/official/xfce/

Mounted a blank dynamically-sized VMDK set to 100GB as the hard drive, and the Manjaro ISO as an optical disk.
Boot the machine, it will default to the ISO since there is no GRUB on the VMDK, and install Manjaro COMPLETELY DEFAULT.
Shut down the VM, un-mount the ISO.
Start VM, should now boot into the Manjaro xfce desktop environment.
Here, I let Manjaro do ALL the updates it wanted to automatically through the Pamac GUI (the default Manjaro Package Manager)
Through Pamac, install meson, gcc, pkgconf, glm, and gobject-introspection.
Grab & run the Wayfire install script git clone https://github.com/WayfireWM/wf-install && cd wf-install && ./install.sh
Run Wayfire with /opt/wayfire/bin/startwayfire