Autofill behavior for PW+OTP combination

There are multiple websites/services that have very simple login forms and do not include a field for the TOTP code. Instead, they ask the user to just append (or prepend) the code to their password. For example this is the case with many firewall/nas/wifi controller (for example Sophos) logins and VPN authentication (like OpenVPN).

This is a very technical and hard to remember step for many users and it would be great if 1Password offered an autofill behavior option (set per item or even website within the item) that copies/autofills the password with the TOTP code already added to it.