I've been working on an OSS project, Amika[1], to quickly spin up local or remote sandboxes for coding workloads. We support copy-on-write semantics locally (well, "copy-and-then-write" for now... we just copy directories to a temp file-tree).
It's tailored to play nicely with Git: spin up sandboxes form CLI, expose TCP/UDP ports of apps to check your work, and if running hosted sandboxes, share the sandbox URLs with teammates. I basically want running sandboxed agents to be as easy as `git clone ...`.
Docs are early and edges are rough. This week I'm starting to dogfood all my dev using Amika. Feedback is super appreciated!
FYI: we are also a startup, but local sandbox mgmt will stay OSS.