Why don’t they simply do it the way it’s done in Switzerland.
You are eligible were ever you are in the world. And you get an amount pro rata for the number of years you worked. Worked 12 y? Eligible to 12/44ths a standard Swiss government pension.
What happens to the years one could be on the dole as a result of redundancy or mentally disabled, physically disabled and unable to work. Forget about them. Like Hell. Be fair That's not the new NZ thinking although it was common in the past which has gone. Times are changing a fair life for all is on the increase.