Hi,
On your link, it says this:
To get started, create your feed offline as a .csv, .tsv, .xls, or xlsx file, then upload it to your account's "Business data" section. If you're a retail business, use the Google Merchant Center to upload your product feed.
If you're using HikaShop, it probably means that you're selling stuff online. So, you must be a "retail business" and not another type of business which doesn't sell stuff. So, what you're pointing out should not apply to you.
On the other end, if you follow the link of the "use the Google Merchant Center to upload your product feed" you get on this page:
support.google.com/merchants/answer/1215...29712-237839881&rd=1
There, you can read this:
What file formats are accepted?
You can use .txt, .xml, or a .tsv. Files can be up to 4 GB in size.
So, you're good with XML.
There, you can also read this:
How do I create a file containing my product data?
The content and format of your product data file are very important and must adhere to our Product data specification. Learn more about creating a product file for Merchant Center.
And this "Product data specification" is precisely what our Google Products plugin follows.