thanks a lot for your answer with your directives and tipps, which fortunately aren’t necessary anymore ??
the cause for the white screen was found located outside of the wp installation on my webserver where an erroneous .htaccess one level up with a directive routing the path */admin/data to 404, which by chance affects the /root/my_wp_installation/wp-content/plugins/woocommerce/assets/client/admin/data/index.js which was identified as missing and causing the unfinished loading of the wc setup wizard (the page was mostly loaded, but stayed invisible).
