How price is displayed from the feed

If you want to display the price from your feed, then the price needs to be added in the XML/feed URL.

Feedzy extracts price in the following order:

1. From an XML element called <price>
2. From an XML element called <price> belonging to the namespace http://base.google.com/ns/1.0. More details - https://support.google.com/merchants/answer/160589?hl=en
3. From an XML element called <CurrentPrice> belonging to the namespace http://www.ebay.com/marketplace/search/v1/services.

That said, the feed needs to have one of the tags and namespaces mentioned above. 

You can customize XML/Feed Structure of a WordPress website using this guide - https://www.wpbeginner.com/wp-tutorials/how-to-create-custom-rss-feeds-in-wordpress/. Note that this is to be done on the website from where the Feed/content is coming, and not on your website where you are importing the posts.