There is a guide here for how to do this by customizing the TOTP_Latest.jsp page: https://community.microfocus.com/t5/Access-Manager-User-Discussions/Customize-TOTP-Account-GUI-on-OTP-Authenticators/m-p/2826505#M7116
This requires we write and maintain this code, then keep it updated per environment. It would be nice to simply have 3 key:value parameters that could be added as properties on the TOTP class. This would allow us to set the attribute for the user, the issuer and the URL.
It appears that NAM is pulling some default attribute values, specifically the host OS hostname (issuer), the CN of the logged in user (user) and the fully qualified hostname (URL). If it could override those in the class properties as mentioned above in the underlying code, we wouldn't need to maintain a customized page.