It says in the article that windows sandbox is using a "base image". It boots up the image, you do stuff then close it, and the next time you boot it up it's the base image again. Is that not what a template VM would do?

The primary difference between a usual VM template and this is that it's small. "When installed the dynamic base package it occupies about 100MB disk space". That's because it's essentially mounting a bunch of the system files immutably. You could theoretically do the same on Linux, but it probably wouldn't be worth the effort.

Most of the advancements they have is under the hood stuff, like linking files instead of directly including them or managing memory. Battery state pass through and graphics OOTB is cool though, depending on your setup you might have to put in a bit of work to make that happen on Linux.