KaiOS - UI Kit
KaiOS is a web-based operating system that powers an eco-system of affordable devices. It enables smartphone like services such as 4G, Mobile payments, and NFC to devices that are a fraction of the cost of low tier devices.
https://www.sketchappsources.com/free-source/3501-kai-os-ui-kit-sketch-freebie-resource.html
If you are designing for users in emerging markets, I hope you will consider a KaiOS port of your application.