Simple Google Sitemap Pro is an advanced version of Simple Google Sitemap. The extension is designed to generate sitemap.xml on Opencart 2.x-3.x.

DEMO:
http://oc3020.helpforsite.com/admin/
demo/demo

Featured:

compatible with OpenCart 2.x & 3.x
compatible with Journal2 template
compatible with Journal3 template
compatible with blog extension Advance News System
has a user-friendly interface in Russian & English
supports multilanguage
can maintain a log of sitemap requests. You will always know what search engine is visiting the site
create sitemap index
splits sitemaps into pages (necessary for large sites)
can work with any number of products
supports lastmod tag
supports image tag
supports additional images of product
supports custom links
can encode special chars in URL
fully customizable

HOW TO INSTALL

At first, go to admin area of your site.

Step 1: Upload extension (zip file) in Extensions -> Extension installer (FTP in System->Settings must be enabled) or unzip files and upload via FTP to your site
Step 2: Go to Extension -> Feeds and Enable Simple Google Sitemap Pro
Step 3: Find in .htaccess the line
RewriteRule ^sitemap.xml$ index.php?route=extension/feed/google_sitemap [L]
and replace it to
RewriteRule ^sitemap.xml$ index.php?route=extension/feed/simple_google_sitemap_pro [L]