If you're an Android user, you may be interested in Aegis [0,1].
It allows you to import data from various formats, either through a file or directly from another app like Authy (needs root access).
It also allows for export options, such as encrypted JSON or unencrypted TXT/HTML. Additionally, it enables backups to file storage, I am using my Nextcloud as a target.
Overall, Aegis is my to-go open-source alternative to Authy.