[mborch]

On MacOS, you have built-in sandboxing via "sandbox-exec" which shouldn't incur any noticeable overhead. It's used by Chrome, Bazel, etc.

Not sure what's available on Windows.

[int_19h]

Windows has a lot of things in this department. https://github.com/microsoft/Windows-Sandbox-Utilities sounds similar to what you describe, but there are also finer-grained APIs: https://learn.microsoft.com/en-us/windows/win32/secauthz/app...