For the new e-commerce application PhocaCart from the Czech programmers Phoca we created a plugin for displaying meta tags - Rich Snippets for Phoca Cart.
The plugin works with microdata and creates complete mandatory and recommended meta tags for Product type information. At the same time, it allows you to display meta tags for breadcrumbs for the entire site (if you don't use the appropriate module from administration).
If you are having issues on your Joomla website then please contact us. We are always excited for challenging Joomla tasks!