These "IP agreements", in my experience, include an "Invention Disclosure" section where you can submit a list of "inventions" that you developed before you took the position. It's supposed to be the blacklist of stuff explicitly excluded by the IP ownership agreement (i.e., you still own it since you "invented" it before you joined the org). Usually they give you a few lines to write these in. My approach has been to provide this as an attachment with an exhaustive list ranging from things I've actually developed all the way to mere ideas that could be realized in some form. Of course, every new time you have to sign one of these, the list should be longer. Each item should be broadly written; they can't be asburdly broad, like "Software to perform transformations on data", but you can undoubtedly find ways to make the item more specific to certain domains, and write in that annoying "cover your bases multiple times" form of legalese, e.g. "Tools, methods, and approaches in distributed and monolithic data aggregation, satisfying static and dynamic reliability constraints".
I reliably hear from HR or contracts that I'm the only one they've seen fill that section out, and certainly to the length I typically provide, but they duly accept it and execute the agreement. I've never seen them send to an IP lawyer or anyone else to screen the list for legitimacy.
Considering how challenging litigating technical IP claims is, I think this should have some amount of reasonable deterrent effect regarding threats or actual wanton IP theft litigation after leaving the org's employ.