Using the built-in reader component: html5QrcodeScanner. View scan results in the dev console
QR code links to example.com
NOTE
ngrok can be used to preview this page on mobile devices for dev, e.g.
ngrok http ${APP_PORT}
This one liner generates a tunnel QR code so you can easily open the tunnel URL generated by ngrok on your device
open $(curl -s http://localhost:4040/api/tunnels | jq ".tunnels[0].public_url" | xargs -I{} echo "https://chart.googleapis.com/chart?cht=qr&chl={}&chs=180x180&choe=UTF-8&chld=L|2")
Or access the page over your LAN. Change config to listen on an IP address and restart the server, e.g.
export APP_LISTEN="https://192.168.0.123"
./up.sh
Follow the instructions here for Chrome DevTools (camera permissions require localhost or HTTPS). Then inspect the mobile device tabs on your host
chrome://inspect#devices