Have you checked out Bitwarden’s custom fields? These are available for all vault item types such as logins and secure notes.
While they are great to use for autofill for additional form fields. They can also be used to store additional data related to an item.
Some things may include:
Site security questions & “answers” (I personally treat each security question as an additional password and do not answer these truthfully)
Card PINs and bank account info
Identity information such as an ID card number, or SSN
Additional secure notes information, such as a PGP Private key
There are multiple different custom field types depending on your needs, but for the secure ones you do not want easily visible to shoulder surfing the Hidden custom field option is a personal favorite.
On a separate note here, as I understand the team is reworking how the Master Password Re-prompt functions to hide the entire item behind the reprompt to prevent from easily viewing notes, TOTP codes, etc.
Though the previous option for the Hidden custom fields is currently available to use and also allows for easy copy of the individual data.