Hello again!
I believe it could be the same:
Vendor_ID or Company_ID
I believe here on forum we are talking about the variable assigned for that:
https://forum.cs-cart.com/t/how-to-get-company-id-from-index-page/2274/8
In the MVE situation can use:
$runtime.company_id and ...
External seller ID [external_seller_id]
Interesting is to be able to put together for each product, in the template of your addon, in the cs-cart mve to give the required function of google "External seller ID" for Marketplaces.
A greeting!