Can I use local/duplicate/Chinese battery in iPhone SE 1st Gen? Will it affect the performance in a negative way? Can it lead to unexpected shutdowns? How long will it last?
There are no certainties and no guarantees with how after market batteries will perform in any device. This is also true for iPhones.
Having said that, it all depends on the quality of the battery how it performs.
Repair services that aren’t certified by Apple have been using after market batteries since forever and apparently it’s not the end of the world.
But it’s also true that devices are prone to be fire hazards if something’s done wrong while installing the battery.
I think it’s not worth the risk to save a few bucks by not going to Apple or an Apple Certified Repair Shop for a battery replacement.