Exporting 2FA codes from one instance of Google Authenticator to another is relatively painless, just use the export QR in the menu and import into another.
However this provides no way to import into another 2FA app, effectively locking their users into the Google ecosystem. The standard format has been wrapped in a proprietary one to prevent users from making a choice of authenticator.
I’ve rejected this reality and subsituted my own by creating an entirely offline way of exporting these codes into the standard format (which ironically was originally developed for the earlier versions of Google Authenticator).
This essentially decrypts the export QR images and displays them as separate standard 2FA QR codes. The app works entirely offline and all logic is performed the browser.
You can find the code (and link to the webapp) at rmp135/GoogleAuthExporter