Unfortunately for the EU, Hungary is part of of block.
Regarding Serbia, if you’re applying, you should behave like a perfect member. Croatia and Estonia are notoriously known to have implemented EU directive as candidates, before the directive were even voted.
Yeah, applied 15 years ago, with the current status of “in a decade, maybe”. It’s just funny how after 4 years of “no more enlargement, EU’s full, structural reform first” suddenly everyone’s pretending like Serbia was on the cusp of membership instead of basically being Turkey 2.