why can't i add stickers to my collection? can i only gift stickers i find to other people or is there something i'm missing lol?

You can, but it costs 10k. You have to visit the hustler in the park in atebus to do it, I can link you if you want.

Stickers were not originally intended to be anoher collection, they were meant to be a social thing.

You can stick them to yourself for 10k per sticker, at the Hustler's Office. Go to Pina Park > Hustler > office, or direct link here. There are also plenty of boards where people offer to stick you for free.

ah okay cool. and sure!

here It's in piña park along the right side.