this addon only accpet bing index ？

IndexNow API (indexnow.org) is an easy way for websites owners to instantly inform search engines and web crawlers used for information retrieval (“search engines”) about latest content changes on their website.

When you create or modify a product in backoffice, IndexNow API is a simple ping so that search engines know that a URL and its content has been added, updated, allowing search engines to quickly reflect this change in their search results.

Without IndexNow, it can take days to weeks for search engines to discover that the content has changed, as search engines don’t crawl every URL often. With IndexNow, search engines know immediately the "URLs that have changed, helping them prioritize crawl for these URLs and thereby limiting organic crawling to discover new content."

IndexNow has support from Microsoft Bing, Naver, Seznam.cz, Yandex, Yep.

description says it supports Bing, Naver, Seznam.cz, Yandex, Yep 。 I purchased it but I found out it only supports bing, I feel like I was scammed, can I get a refund?

Search engines adopting the IndexNow protocol agree that submitted URLs will be automatically shared with all other participating search engines.

Our module uses: const engine="https://www.bing.com/indexnow";

You can also change the default url by:
https://api.indexnow.org/indexnow
https://searchadvisor.naver.com/indexnow
https://search.seznam.cz/indexnow
https://yandex.com/indexnow
https://indexnow.yep.com/indexnow

A new version is available, in which you can choose the default search engine in configuration.