AFAIK, few people attempt to do this.
Only people like Zisworks tries to do this kind of stuff.
It's because
it costs more to modify the monitor than to just buy a new monitor, and there isn't economies of scale to compensate (e.g. like jailbreaking an iPhone). In many cases, the language of the .bin file is unknown. And custom firmware mods aren't reusable.
One can use ToastyX Custom Resolution Utility to "force" FreeSync into a non-FreeSync display and see what happens; sometimes that works; you're at the mercy of the firmware quirks and behaviours for the most part.
If this monitor is out of warranty, you got assembler / machine language / disassembly experience, and you'd like to proceed as an academic exercise, and you attempt to modify the firmware anyway -- post in the Area 51 forum (Display Science, Research & Engineering) -- I'd be interested in reading about it!