Yes & yes.
Since you already migrated from Google Authenticator to the Bitwarden Standalone Authenticator app, you can use this method to export a .JSON file from the Bitwarden Authenticator:
You can then import the .JSON into your Bitwarden Password Manager, using the following instructions, and selecting “Bitwarden (json)” as the file format:
However, beware: If your Bitwarden Password Manager vault already has data for the login credentials (username and password), then importing the TOTP data from a .JSON file will not merge the data — you will get separate vault items for the TOTP data.
As a work-around, you could export your TOTP codes from the Bitwarden Authenticator in .CSV format, export your vault data from the Bitwarden Password Manager in .CSV format, then manually combine them (which would primarily involve sorting both files in a way that all rows line up, then copying the login_totp column data from the Authenticator export into the same column in the Password Manager export). You would then purge the contents of your Password Manager vault, and import the consolidated .CSV file.
Obviously there are risks involved if you are purging your Bitwarden Password Manager vault. Depending on what type of data you have in your vault, and whether you have backups, you may need additional guidance to prevent data loss.