For building widgets you can follow Mendix documentation for it https://docs.mendix.com/howto/extensibility/create-a-pluggable-widget-one/.
And also second option will be (not recommending as a great option) you can find some widget on martketplace and just adjust code how ever you want. But definitely building your own widget is better option.
Best regards, Slavko
I'm building my own custom widget for showing calendars with only years. I couldn't find any react native packages available .Can you please suggest me some of the packages?
Thanks in Advance,