These are not mutually exclusive, and one makes the other better. "Whole process" sandboxing has always been far worse than native sandboxing because when the devs writing the software design the software to be sandboxed they can achieve far more fine grained permissions. Similarly, "whole environment" sandboxes are the absolute worst - they're the least fine grained possible.

The benefit of "whole environment" is that if you stuff everything into that environment then anything in it is confined, but it's all confined with everything stuffed in and is sort of maximally capable. You can rarely do things are significant as, say, system call filtering, because all software in the environment must continue to work and none of it was designed with that in mind.

Native sandboxing like this will likely make auditing much easier as well. If a dependency requires something like "give me the ability to execute code on the OS", now it has to ask for it and now it gets additional scrutiny.

Native sandboxing is and always will be the infinitely superior method when it's actually used. Whole process/ Environment is only what we use because of how rare native sandboxing is.