While looking for a way to download an .ISO file for Ubuntu Core, I ran into this tutorial for installing Ubuntu on a VirtualBox 7 Virtual Machine. If you've been intrigued by the idea of using VMs to explore other distros and DEs without installing them on hardware, but didn't know how to get started, this might be for you.
Of course, being from Canonical, this is aimed at creating an Ubuntu VM. However, the main difference is just the .ISO file used for the process.