Optional things for development are optional so won't always be used. I guess rather than saying "this is a unix program" you could say, this is an OpenBSD program. Which would mean that it has undergone a set of processes for development where all the optional things are not turned off. For example: code review, static analysis, fuzz/quickcheck style testing, using pledge() appropriately, etc. But you'd need to define the set of processes that need to be followed before it could be called an 'OpenBSD program'. Replace 'OpenBSD program' with whatever you want to call this.

Who should set up the permissions? If you trust the developers, you trust them to set up the permissions for you. However, what happens of you don't trust them? You need administrators and users to be able to tweak what the programs are allowed to do.

What is really great about doing it at the developer level is that the administrator do not need to think about that stuff.

For large programs like emacs, or python, it is unfortunate that you can't disable the privs just for a functional call for example. I'd like to see a discussion on why this wouldn't work? I guess there is a good reason - but they don't say.

If you "allow only these privs until Done" where Done would be defined by the program jumping back to a point set by pledge() call. If the process does not allow writing on executable memory this would work (at least for non jit processes).

I wonder if there are ways this can be used by python. Perhaps using a fork this could be done. The program forks to run just the priv bit of code. It can use pledge() and drop all the stuff it doesn't need - do it's business - then die.