There is the Hyper-V Server 2019 [0] too which was also free and a standalone OS unlike the current version. I use that on a 2nd PC, you can also install a full GUI [1] on top of the webadmin interface so pretty good actually.
Anyone reading this, don't expect a smooth experience for desktop Linux under Hyper-V.
Hyper-V's team only cares about supporting servers. You're not gonna run a full-screen Ubuntu VM without a lot of banging your head against the wall, unless you spend days trawling random Github comments and reddit posts and fixing it whenever it breaks.
yeah Windows Sandbox is pretty great. I use it to test sketchy software when sailing the high seas. And the option to add shared readonly folders on the host OS is nice too.
Windows also has Sandbox (based on container technology), which replaces creating a VM to test some software without affecting the system.