As a Nix user, I'm actually really excited to try this out.

I want to run sandboxes based on Docker images that have Nix pre-installed. (Once the VM boots, apply the project-specific Flake, and then run Docker Compose for databases and other supporting services.) In theory, an easy-to-use, fully isolated dev environment that matches how I normally develop, except inside of a VM.

Microsandbox's primary goal is to make it easy to build environments for running untrusted code.

Nix, on the other hand, solves the problem of building reproducible environments... but making said environments safe for running untrusted code is left as an exercise for the reader.