Hi,
yes, Google accepts the gzip-compressed sitemaps:
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When the generator script sends ping request to Google, they read the sitemap file from your host. Then it may take few hours before they will parse your sitemap. And after that they will crawl your site to index the pages you listed in sitemap - this may take longer time (it depends on many things). So, the generator ensures to collect all you pages and informs Google with the full list, making it easier to crawl your site.