Thank you all! We found it in a food supply store (the type that sells ingredients, spices, mixes etc to stores and food places) and the person from the company had also replied saying they can be purchased in SSiong as most of you kindly pointed out. Thank you!
My grandma bought from provision shop at wet market
Provision shop, Prime and Giant supermarket
I've seen this in sheng shiong
Giant, sheng shiong have those
Sheng Siong.
Sheng shiong confirm have
Saw it in sheng shiong
Giant shengsheong
Try sheng shiong