(I am actually doing this on Leap 15.4, not on Tumbleweed).
It is not sufficient to change this only in the www.conf file, you also have to change the line starting with fastcgi_pass in the /etc/nginx/nginx.conf file.
Then there is no need to chown nginx:nginx for the .pid and .sock files. Just ignore these instructions. You can start the php-fpm service right away. Of course, you have to restart the nginx service, too.
Please, please. Hanging on a post at the end of such an old thread is not very useful. As you say yourself, you are using another openSUSE version and in the meantime many things will have been changed.
If you want attention to a problem, better start a new thread with a good title to draw the attention of the people you need for help.