As long as we are not talking WW3, Russia is hands down best place to be, it could easily stay cohesive with a lower standard of living, has been switching to internal supply chains for a decade now, has swaths of empty land and population not foreign to a concept of living off land, but most importantly it is under populated.

Low population density - check

Good defense - check

Cultural and societal background necessary for a post collapse - check

Carrying capacity of land - check

Energy (oil/atomic) - check

Nukes - check

Base of LOWER(more resilient to supply chain disruptions) tech industry - check

Benefits from climate change - check