According to the OpenBSD FAQ #10:
If you want to give access to superuser privileges without adding users to the wheel group, use sudo(8).
According to the OpenBSD man pages on sudo(8):
sudoedit [-AnS] [-a auth_type] [-C fd] [-c class | -] [-g group name | #gid] [-p prompt] [-u user name | #uid] file ... ... -A Normally, if sudo requires a password, it will read it from the user's terminal. If the -A (askpass) option is specified
-A is ask for password, and not add a user to the sudoer's group. It appears none of
-AknS adds a user to the group.
sudoedit -u <useranme> just prints help, and does not add the user to the sudoer's group.
How do we add a user to the sudoer's group?
A related question is How can I add a regular user to the sudoers file?. But it states to edit
/etc/sudoers directly, which the man pages don't tell me to do. (Plus, I've learned that the BSDs are different enough from Linux so that we should not blindly follow Linux advice).