Welcome to Singapore. I hope you enjoyed your short stay over here.
There isn't really seats for locals, only those for pregnant and the elderly (and those are usually just a few seats for every passenger cabin). I can assure you that any local who insists anyone else gives up their seat are just the weird boomers/karens looking to bully someone. I sure do hope if you ever meet someone like that, you won't think that is representative of our country.
We are generally pretty helpful and nice, although we don't make small talk. (so if you need help just ask)