1 - I have no experience with Heroku.com so I cannot help you there.
2 - on this forum (
https://www.mobileread.com/forums/sh...d.php?t=282871) using Google drive with calibre (and thus COPS) is not encouraged (just don't do it!)
It's not clear to me if that is even possible.
3 - to access a calibre library on your own laptop (MacBook?) you need to:
a. make the library on your laptop available (share) to heroku.com on the web (trough for instance samba). I would say, just don't do that for security reasons, even if it's possible (no idea).
b. mount that share in Hedoku.com.
c. point COPS config_local.php to those mounts (did not work for me on a debian-linux server)
example:
$config['calibre_directory'] = array ("My database name" => "/mounted/directory/calibre1/", "My other database name" => "/mounted/directory/calibre2/");
Sorry I cannot be of more help.
PS: I'm no native English speaker either so no worries there.