WhatsApp has introduced a small improvement with the latest update: You can directly answer privately from group chats to one person.
To do this, tap on the chat content of the person you want to reply to for a while and then select “More” in the context menu and then “Private reply”. This will land you in the private chat with the selected person. Nothing earth-shattering but a practical abbreviation. This saves you going back to the chat overview and searching for the corresponding private chat.
A practical solution to address things that do not belong in the public group chat.