otpauth VS otpauth-migration-decoder

will generate a PNG file for each account, name after the account name and site name, and containing the QR code for the account.

Going forward, save those PNGs somewhere secure (I use an encrypted tar file). Any new accounts you set up save the QR codes for those as PNGs and add them to your collection. If you keep that collection up to date you will be able to readily handle any device updates or replacements readily or adding new TOTP apps.

[1] https://github.com/dim13/otpauth

afterwards you can use https://github.com/dim13/otpauth to convert the GAUTH code to plaintext

Open google authenticator, export accounts, screenshot QR code, decode with cyberchef, decode otpauth-migration link with https://github.com/dim13/otpauth

Scan the code with something else and pass the string inside to a tool like this in order to get the individual tokens/codes: https://github.com/dim13/otpauth

latest google authenticator has an export option. save the url or QR code and you will be able to load it in the next phone (or use a tool such as https://github.com/dim13/otpauth / https://github.com/digitalduke/otpauth-migration-decoder to decode the keys/timers and load in TOTP inside keypassx etc')

The code on this page is a standard otpauth string.

Not tested yet but this tool should allow you to create scanable QR codes for other auth apps as far as I understand. https://github.com/dim13/otpauth

latest google authenticator has an export option. save the url or QR code and you will be able to load it in the next phone (or use a tool such as https://github.com/dim13/otpauth / https://github.com/digitalduke/otpauth-migration-decoder to decode the keys/timers and load in TOTP inside keypassx etc')