We all know this amazing quickchart.io that @jared had mentioned. but if it’s hiding
as per it’s easy to integrate with thunkable.no worries 
. just put this:
quickchart.io/qr?text=Data
in image component. try using this sample app called “bacn” for more info.
https://x.thunkable.com/projects/61544891804fe10010c87131/preview/c14d5c3a-e176-49a8-86fc-c04fcf32b262
you could manage anything.
https://quickchart.io/documentation/#qr