https://github.com/golang/go/issues/26463

1. $HOME should be used, if available, as user's home directory. Quoting http://man7.org/linux/man-pages/man3/getpwuid_r.3.html:

The pw_dir field contains the name of the initial working directory
of the user. Login programs use the value of this field to
initialize the HOME environment variable for the login shell. An
application that wants to determine its user's home directory should
inspect the value of HOME (rather than the value
getpwuid(getuid())->pw_dir) since this allows the user to modify
their notion of "the home directory" during a login session.

2. Tilde Expansion
   https://stackoverflow.com/questions/20504662/how-to-get-home-directory-of-different-user-in-bash-script

In that case, the simplest solution is to use tilde expansion with the username of interest, combined with eval (which is needed, because the username must be given as an unquoted literal in order for tilde expansion to work):

eval echo "~$different_user"    # prints $different_user's home dir.