Simple Android app to show whatever text is on the clipboard as a QR code.
This was a quick hack, developed years ago for a single task. It requires no permissions but does capture text copied to the clipboard. It should work on current Android but has only been tested on Android 7 and below.
Quick build instructions on the wiki - https://github.com/anomie-tech/qrdisplay/wiki
Possible alternative (not yet vetted) for Browsers: https://github.com/rugk/offline-qr-code