Thank you for this application!
https://github.com/helloworld1/FreeOTPPlus is a popular OTP app with over 50,000 users (https://github.com/helloworld1/FreeOTPPlus). It has an "export to JSON" function.
Would you consider adding import from their export format? (My use case is wanting to use your app on the desktop without having to re-set-up every single key individually).