Should you be honest or nah?

Why are you leaving in the first place ? If you are leaving for pay, career growth you can be upfront. Other issues you need to thread safely if you don't want to burn any bridges.

Just be politically right and get the hell out of that place

My exit interview for MS was done by a contractor. I was brutally honest. I wouldn't sweat it too much unless you named names

Is there a threshold you cross from, "this sucks and I wish I could say something without that honesty being used against me" to "this sucks for the people under me but their HR complaints don't impact my performance"? Is that a Director level or??

Don’t. Be nice. Do not burn bridges, not worth it.