NOT THE HECKING SANDNIGGERINOOS. But seriously, Ukrainian grain exports this year will be non-existant anyway, and we have banned grain exports ourselves.
It won't be classic regime change like in Iraq, more of the USSR collapse 2.0. Nukes are relatively well defended, their locations are known and they can be quickly put under joint custody (and that's what newly formed government will likely do, as Ukraine did in 1991, for example).
If scenario 2 is not enacted now, it will be enacted after scenario 1. But after scenario 1 you'd have war-torn country, possibly with NATO or Chinese occupational forces within its borders (as a result of devastating defeat), with much less intact infrastructure and industrial capacity, DPRK-tier economy and shittier human capital. Good luck fixing that.