Use Aegis, an open source 2FA. Google Authy is closed source.
Just for the clarification, does Aegis supports online backing up of the 2FA keys?
snipYou can backup to Google Drive for example[1]. If you want to manually make a backup of your file, then it will be saved on a folder in the local device. However, if you choose to "Export" your encrypted vault the program allows you to save your file in a cloud provider, provided that you have it installed.
[1]
https://github.com/beemdevelopment/Aegis/issues/258